An Overview on Gripping Force Measurement at the Micro and Nano-Scales Using Two-Fingered Microrobotic Systems
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paper_title: Manipulation at the NanoNewton level: Micrograpsing for mechanical characterization of biomaterials

paper_content:

This paper presents the use of a monolithic, force-feedback MEMS (microelectomechanical systems) microgripper for characterizing both elastic and viscoelastic properties of highly deformable hydrogel microcapsules (15–25µm) at wet state during micromanipulation. The single-chip microgripper integrates an electrothermal microactuator and two capacitive force sensors, one for contact detection (force resolution: 38.5nN) and the other for gripping force measurements (force resolution: 19.9nN). Through nanoNewton force measurements, closed-loop force control, and visual tracking, the system quantified Young's modulus values and viscoelastic parameters of alginate microcapsules, demonstrating an easy-to-operate, accurate compression testing technique for characterizing soft, micrometer-sized biomaterials.
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paper_title: Autonomous micromanipulation using a new strategy of accurate release by rolling

paper_content:

This paper presents our work in developing an autonomous micromanipulation system. The originality of our system is that it takes advantage of adhesion to grip micro-objects by using a single fingered gripper. This is in fact a tipless cantilever previously designed for atomic force microscopy applications. We describe vision techniques employed to process images provided by an optical microscope, allowing to position accurately the end-effector for a gripping task. A theoretical study of the direct force measurement device and an experimental validation show how we can improve the measurement of impact and contact forces. Then we explain the strategy used to bring the gripper into contact with the object, based on force control and kinematic redundancy. Finally, a simplified model of the release task is proposed in order to determine conditions that allow to roll the object, and then to place it with precision.
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paper_title: Quadrilateral Modelling and Robust Control of a Nonlinear Piezoelectric Cantilever

paper_content:

Piezocantilevers are commonly used for the actuation of micromechatronic systems. These systems are generally used to perform micromanipulation tasks which require high positioning accuracy. However, the nonlinearities, i.e., the hysteresis and the creep, of piezoelectric materials and the influence of the environment (vibrations, temperature change, etc.) create difficulties for such a performance to be achieved. Various models have been used to take into account the nonlinearities but they are often complex. In this paper, we study a one degree of freedom piezoelectric cantilever. For that, we propose a simple new model where the hysteresis curve is approximated by a quadrilateral and the creep is considered to be a disturbance. To facilitate the modelling, we first demonstrate that the dynamic hysteresis of the piezocantilever is equivalent to a static hysteresis, i.e., a varying gain, in series with a linear dynamic part. The obtained model is used to synthesize a linear robust controller, making it possible to achieve the performances required in micromanipulation tasks. The experimental results show the relevance of the combination of the developed model and the synthesized robust H infin controller.
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paper_title: Optical tweezers: the next generation

paper_content:

JOHANNES Kepler is famous for discovering the laws of planetary motion, but he is less well known for writing what may have been the first science-fiction story to involve space travel. During his observations, the German astronomer noticed that tails of comets always point away from the Sun, which suggested that the Sun was exerting a sort of radiant pressure. This led him in 1609 – the year in which he published the first of his laws – to propose sailing from the Earth to the Moon on light itself. Of course, that was and still is the stuff of science fiction, but 400 years later Kepler's initial ideas about moving matter with light are very much a reality.
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paper_title: Force feedback-based microinstrument for measuring tissue properties and pulse in microsurgery

paper_content:

Miniaturized and "smart" instruments capable of characterizing the mechanical properties of tiny biological tissues are needed for research in biology, physiology and biomechanics, and can find very important clinical applications for diagnostics and minimally invasive surgery (MIS). We are developing a set of robotic microinstruments designed to augment the performance of the surgeon during MIS. These microtools are intended to restore (or even enhance) the finger palpation capabilities that the surgeon exploits to characterize tissue hardness and to measure pulsating vessels in traditional surgery, but that are substantially reduced in MIS. The paper describes the main features and the performance of a prototype miniature robotic instrument consisting of a microfabricated microgripper, instrumented with semiconductor strain-gauges as force sensors. For the (in vitro) experiments reported in the paper, the microgripper is mounted on a workstation and teleoperated. A haptic interface provides force feedback to the operator. We have demonstrated that the system can discriminate tiny skin samples based on their different elastic properties, and feel microvessels based on pulsating fluid flowing through them.
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paper_title: Magnetic separation techniques: their application to medicine

paper_content:

Whilst separation techniques relying on gravitational forces have become relatively sophisticated in their application to biology the same is not true for magnetic separation procedures. The use of the latter has been limited to the few cells which contain paramagnetic iron. However with the development of several different types of magnetic particles and selective delivery system (e.g. monoclonal antibodies) the use of magnetic separation techniques is growing rapidly. This review describes the different types of particles currently available, the magnetic separation technique applied to the different magnetic compounds and illustrates major uses to which magnetic separation procedures are currently applied in the area of biology and medicine.
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paper_title: Vacuum tool for handling microobjects with a NanoRobot

paper_content:

One of the basic tasks a robot has to perform is to manipulate objects. For macroscopic applications mechanical grippers usually grasp the workpiece. Because of the different scaling of gravity and adhesion such tools are no more suitable in micro manipulation. A better strategy is to use adhesion forces or vacuum. Therefore, after a brief introduction to adhesion phenomenons this paper focuses on the investigation of a vacuum gripping tool consisting of a glass pipette and a computer controlled vacuum supply. Special emphasis is laid on the optimization of the tool's parameters in order to improve its pick and place capability. The tool has been integrated into the ETHZ NanoRobot and tested on dedicated benchmark test. It was possible to grip 100 /spl mu/m sized diamond crystals and deposit them at arbitrary positions. Also emergency routines that allow to reliably get rid of sticking particles are presented. Finally the new setup of the multi-tool NanoRobot containing both the vacuum pipette and a microfabricated gripper is presented. It enables handling of micro-parts with more flexibility by working hand in hand.
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paper_title: Modeling the trajectory of a microparticle in a dielectrophoresis device

paper_content:

Micro- and nanoparticles can be trapped by a nonuniform electric field through the effect of the dielectrophoretic principle. Dielectrophoresis (DEP) is used to separate, manipulate, and detect microparticles in several domains, such as in biological or carbon nanotube manipulations. Current methods to simulate the trajectory of microparticles under a DEP force field are based on finite element model (FEM), which requires new simulations when electrode potential is changed, or on analytic equations limited to very simple geometries. In this paper, we propose a hybrid method, between analytic and numeric calculations and able to simulate complex geometries and to easily change the electrode potential along the trajectory. A small number of FEM simulations are used to create a database, which enables online calculation of the object trajectory as a function of electrode potentials.
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paper_title: Overview of Microgrippers and Design of a Micromanipulation Station Based on a MMOC Microgripper

paper_content:

This paper deals with an overview of recent microgrippers. As the end-effectors of micromanipulation systems, microgrippers are crucial point of such systems for their efficiency and their reliability. The performances of current microgrippers are presented and offer a stroke extending from 50mum to approximately 2 mm and a maximum forces varying from 0.1 mN to 600 mN. Then, micromanipulation system based on a piezoelectric microgripper and a SCARA robot is presented
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paper_title: Resource Letter: LBOT-1: Laser-based optical tweezers.

paper_content:

This Resource Letter provides a guide to the literature on optical tweezers, also known as laser-based, gradient-force optical traps. Journal articles and books are cited for the following main topics: general papers on optical tweezers, trapping instrument design, optical detection methods, optical trapping theory, mechanical measurements, single molecule studies, and sections on biological motors, cellular measurements and additional applications of optical tweezers.
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paper_title: Improvement of Strain Gauges Microforces Measurement using Kalman Optimal Filtering

paper_content:

Manipulation of small components and assembly of microsystems require force measurement. In the microworld (the world of very small components), signal/noise ratio is very low due to the weak amplitude of the signals. To be used in feedback control or in a micromanipulation system, a force sensor must allow static and dynamic measurements. In this paper, we present a micro-force measurement system based on the use of strain gauges and a Kalman optimal filter. Using a model of the measurement system and a statistical description of the noise, the optimal filter allows filtering the noise without loss of dynamic measurement. The performances of the measurement system are improved and fast force variations can be measured.
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paper_title: Squeeze film air bearings using piezoelectric bending elements

paper_content:

Reference LSA-CONF-2000-016 Conference Web Site: http://server.woomeranet.com.au/~movic2000/default.html Record created on 2006-12-07, modified on 2016-08-08
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paper_title: A micro-particle positioning technique combining an ultrasonic manipulator and a microgripper

paper_content:

The acoustic radiation force acts on particles suspended in a fluid in which acoustic waves are present. It can be used to establish a force field throughout the fluid volume capable of positioning the particles in predictable locations. Here, a device is developed which positions the particles in a single line by the sequential use of two excitation frequencies which have been identified by a finite element model of the system. The device is designed such that at one end there is an opening which allows the fingers of a microgripper to enter the fluid chamber. Hence the gripper can be used to remove the last particle in the line. The high accuracy of the positioning of the particles prior to gripping means that the microgripper needs just to return to a fixed position in order to remove subsequent particles. Furthermore, the effects of the microgripper fingers entering the fluid volume whilst the ultrasound field is excited are examined. One result being the release of a particle stuck to a gripper finger. It is believed that this combination of techniques allows for considerable scope in the automation of microgripping procedures.
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paper_title: Design, fabrication, and testing of a 3-DOF HARM micromanipulator on (1 1 1) silicon substrate

paper_content:

In this study, a novel HARM (high aspect ratio micromachining) micromanipulator fabricated on (1 1 1) silicon wafer is reported. The micromanipulator consists of a positioning stage, a robot arm, supporting platforms, conducting wires, and bonding pads. These components are monolithically integrated on a chip through the presented processes. The three-degrees-of-freedom (3-DOF) positioning of the micromanipulator is realized by using the integration of two linear comb actuators and a vertical comb actuator. The robot arm is used to manipulate samples with dimension in the order of several microns to several hundred microns, for instance, optical fibers and biological samples. The robot arm could be a gripper, a needle, a probe, or even a pipette. Since the micromanipulator is made of single crystal silicon, it has superior mechanical properties. A micro gripper has also been successfully designed and fabricated. © 2005 Published by Elsevier B.V.
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paper_title: Development of a tactile low-cost microgripper with integrated force sensor

paper_content:

This paper describes recent results of the development of a novel tactile force-sensing microgripper based on a flexure hinge fabricated in stainless steel by wired electro discharge machining (EDM). The gripper was equipped with a commercial semiconductor strain-gauge and a piezo stack. The microgripper is an end-effector of a microrobot developed to grasp and manipulate tiny objects. Acquiring force-information with the microgripper is of fundamental importance in order to achieve the dexterity and sensing capabilities required to perform micromanipulation or assembly tasks.
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paper_title: Capillary self-alignment assisted hybrid robotic handling for ultra-thin die stacking

paper_content:

Ultra-thin dies are difficult to package because of their fragility and flexibility. Current ultra-thin die integration technology for 3D microsystems relies on robotic pick-and-place machines and machine vision, which has rather limited throughput for high-accuracy assembly of fragile ultra-thin dies. In this paper, we report a hybrid assembly strategy that consists of robotic pick-and-place using a vacuum micro-gripper, and droplet self-alignment by capillary force. Ultra-thin dies with breakable links are chosen as part of the assembly strategy. Experimental results show that we can align ultra-thin (10μm) dies with sub-micron accuracy without machine vision. A fully automatic sequence of stacking several of these dies is demonstrated. Up to 12 ultra-thin dies have been stacked. These early results show that die-to-die integration of ultra-thin dies with higher throughput than the current industry robot is possible by applying both robotic handling and droplet self-alignment to ultra-thin die assembly.
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paper_title: A hybrid-type electrostatically driven microgripper with an integrated vacuum tool

paper_content:

Abstract Reliable and accurate pick and release of microobjects is a long-standing challenge at the microscale manipulation field. This paper presents a new hybrid type of microelectromechanical systems (MEMS) microgripper integrated with an electrostatic mechanism and vacuum technology to achieve a reliable and accurate manipulation of microobjects. The microgripper is fabricated by a surface and bulk micromachining technology. Vacuum pipelines are constructed by bonding technique. The pick and release micromanipulation of microobjects is accomplished by electrostatic driving force caused by comb structure and an auxiliary air pressure force from air pump. A deflection of 25 μm at the tip of the gripper is achieved with the applied voltage of 80 V. The performance of this new hybrid type of microgripper was experimentally demonstrated through the manipulation of 100–200 μm polystyrene balls. Experimental results show that this microgripper can successfully fulfil the pick and release micromanipulation. Theoretical analyses were conducted to have a more comprehensive understanding of the release principle. Based on this paper, the new kind of hybrid microgripper will possibly provide an effective solution to the manipulation of submicrometer-sized objects.
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paper_title: Haptic Teleoperation for 3-D Microassembly of Spherical Objects

paper_content:

In this paper, teleoperated 3-D microassembly of spherical objects with haptic feedback is presented. A dual-tip gripper controlled through a haptic interface is used to pick-and-place microspheres (diameter: 4-6 μm). The proposed approach to align the gripper with the spheres is based on a user-driven exploration of the object to be manipulated. The haptic feedback is based on amplitude measurements from cantilevers in dynamic mode. That is, the operator perceives the contact while freely exploring the manipulation area. The data recorded during this exploration are processed online and generate a virtual guide to pull the user to the optimum contact point, allowing correct positioning of the dual tips. A preliminary scan is not necessary to compute the haptic feedback, which increases the intuitiveness of our system. For the pick-and-place operation, two haptic feedback schemes are proposed to either provide users with information about microscale interactions occurring during the operation, or to assist them while performing the task. As experimental validation, a two-layer pyramid composed of four microspheres is built in ambient conditions.
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paper_title: Noise characterization in millimeter sized micromanipulation systems

paper_content:

Abstract Efficient and dexterous manipulation of very small (micrometer and millimeter sized) objects require the use of high precision micromanipulation systems. The accuracy of the positioning is nevertheless limited by the noise due to vibrations of the end effectors making it difficult to achieve precise micrometer and nanometer displacements to grip small objects. The purpose of this paper is to analyze the sources of noise and to take it into account in dynamic models of micromanipulation systems. Environmental noise is studied considering the following sources of noise: ground motion and acoustic noises. Each source of noise is characterized in different environmental conditions and a separate description of their effects is investigated on micromanipulation systems using millimeter sized cantilevers as end effectors. Then, using the finite difference method (FDM), a dynamic model taking into account studied noises is used. Ground motion is described as a disturbance transmitted by the clamping to the tip of the cantilever and acoustic noises as external uniform and orthogonal waves. For model validation, an experimental setup including cantilevers of different lengths is designed and a high resolution laser interferometer is used for vibration measurements. Results show that the model allows a physical interpretation about the sources of noise and vibrations in millimeter sized micromanipulation systems leading to new perspectives for high positioning accuracy in robotics micromanipulation through active noise control.
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paper_title: Manipulation at the NanoNewton level: Micrograpsing for mechanical characterization of biomaterials

paper_content:

This paper presents the use of a monolithic, force-feedback MEMS (microelectomechanical systems) microgripper for characterizing both elastic and viscoelastic properties of highly deformable hydrogel microcapsules (15–25µm) at wet state during micromanipulation. The single-chip microgripper integrates an electrothermal microactuator and two capacitive force sensors, one for contact detection (force resolution: 38.5nN) and the other for gripping force measurements (force resolution: 19.9nN). Through nanoNewton force measurements, closed-loop force control, and visual tracking, the system quantified Young's modulus values and viscoelastic parameters of alginate microcapsules, demonstrating an easy-to-operate, accurate compression testing technique for characterizing soft, micrometer-sized biomaterials.
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paper_title: Automated nanohandling by microrobots

paper_content:

The rapid development of nanotechnology has created a need for advanced nanohandling tools and techniques. One active branch of research in this area focuses on the use of microrobots for automated handling of micro- and nanoscale objects. Automated Nanohandling by Microrobots presents work on the development of a versatile microrobot-based nanohandling robot station inside a scanning electron microscope (SEM). The SEM serves as a powerful vision sensor, providing a high resolution and a high depth of focus, allowing different fields of application to be opened up. The pre-conditions for using a SEM are high-precision, user-friendly microrobots which can be integrated into the SEM chamber and equipped with application-specific tools. Automated Nanohandling by Microrobots introduces an actuation principle for such microrobots and presents a new robot design. Different aspects of this research field regarding the hardware and software implementation of the system components, including the sensory feedback for automated nanohandling, are discussed in detail. Extensive applications of the microrobot station for nanohandling, nano-characterization and nanostructuring are provided, together with the experimental results. Based upon the Microrobotics course for students of computer sciences and physics at the University of Oldenburg, Automated Nanohandling by Microrobots provides the practicing engineer and the engineering student with an introduction to the design and applications of robot-based nanohandling devices. Those unfamiliar with the subject will find the text, which is complemented throughout by the extensive use of illustrations, clear and simple to understand.
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paper_title: Microrobotic cell injection

paper_content:

Advances in microbiology demonstrate the need for manipulating individual biological cells, such as for cell injection which includes pronuclei injection and intracytoplasmic injection. Conventionally, cell injection has been conducted manually. In this paper, we present a microrobotic system capable of performing automatic embryo pronuclei DNA injection autonomously and semi-autonomously through a hybrid visual servoing control scheme. After injection, the DNA injected embryos were transferred into a pseudopregnant foster female mouse to reproduce transgenic mice for cancer studies. Experimental results show that the injection success rate was 100%. The system setup, hybrid control scheme and other important issues in this application, such as automatic focusing, are discussed.
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paper_title: NanoLab: A nanorobotic system for automated pick-and-place handling and characterization of CNTs

paper_content:

Carbon nanotubes (CNTs) are one of the most promising materials for nanoelectronic applications. Before bringing CNTs into large-scale production, a reliable nanorobotic system for automated handling and characterization as well as prototyping of CNT-based components is essential. This paper presents the NanoLab setup, a nanorobotic system that combines specially developed key components such as electrothermal microgrippers and mobile microrobots inside a scanning electron microscope. The working principle and fabrication of mobile microrobots and electrothermal microgripper as well as their interaction and integration is described. Furthermore, the NanoLab is used to explore novel key strategies such as automated locating of CNTs for pick-and-place handling and methods for electrical characterization of CNTs. The results have been achieved within the framework of a European research project where the scientific knowledge will be transfered into an industrial system that will be commercially available for potential customers.
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paper_title: Improvement of Strain Gauges Microforces Measurement using Kalman Optimal Filtering

paper_content:

Manipulation of small components and assembly of microsystems require force measurement. In the microworld (the world of very small components), signal/noise ratio is very low due to the weak amplitude of the signals. To be used in feedback control or in a micromanipulation system, a force sensor must allow static and dynamic measurements. In this paper, we present a micro-force measurement system based on the use of strain gauges and a Kalman optimal filter. Using a model of the measurement system and a statistical description of the noise, the optimal filter allows filtering the noise without loss of dynamic measurement. The performances of the measurement system are improved and fast force variations can be measured.
---
paper_title: Automated nanohandling by microrobots

paper_content:

The rapid development of nanotechnology has created a need for advanced nanohandling tools and techniques. One active branch of research in this area focuses on the use of microrobots for automated handling of micro- and nanoscale objects. Automated Nanohandling by Microrobots presents work on the development of a versatile microrobot-based nanohandling robot station inside a scanning electron microscope (SEM). The SEM serves as a powerful vision sensor, providing a high resolution and a high depth of focus, allowing different fields of application to be opened up. The pre-conditions for using a SEM are high-precision, user-friendly microrobots which can be integrated into the SEM chamber and equipped with application-specific tools. Automated Nanohandling by Microrobots introduces an actuation principle for such microrobots and presents a new robot design. Different aspects of this research field regarding the hardware and software implementation of the system components, including the sensory feedback for automated nanohandling, are discussed in detail. Extensive applications of the microrobot station for nanohandling, nano-characterization and nanostructuring are provided, together with the experimental results. Based upon the Microrobotics course for students of computer sciences and physics at the University of Oldenburg, Automated Nanohandling by Microrobots provides the practicing engineer and the engineering student with an introduction to the design and applications of robot-based nanohandling devices. Those unfamiliar with the subject will find the text, which is complemented throughout by the extensive use of illustrations, clear and simple to understand.
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paper_title: Development of a piezoelectric polymer-based sensorized microgripper for microassembly and micromanipulation

paper_content:

This paper presents the design, fabrication, and calibration of a piezoelectric polymer-based sensorized microgripper. Electro discharge machining technology is employed to fabricate the superelastic alloy-based microgripper. It was experimentally tested to show the improvement of mechanical performance. For integration of force sensor in the microgripper, the sensor design based on the piezoelectric polymer PVDF film and fabrication process are presented. The calibration and performance test of the force sensor-integrated microgripper are experimentally carried out. The force sensor-integrated microgripper is applied to fine alignment tasks of micro opto-electrical components. Experimental results show that it can successfully provide force feedback to the operator through the haptic device and play a main role in preventing damage of assembly parts by adjusting the teaching command.
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paper_title: Manipulation at the NanoNewton level: Micrograpsing for mechanical characterization of biomaterials

paper_content:

This paper presents the use of a monolithic, force-feedback MEMS (microelectomechanical systems) microgripper for characterizing both elastic and viscoelastic properties of highly deformable hydrogel microcapsules (15–25µm) at wet state during micromanipulation. The single-chip microgripper integrates an electrothermal microactuator and two capacitive force sensors, one for contact detection (force resolution: 38.5nN) and the other for gripping force measurements (force resolution: 19.9nN). Through nanoNewton force measurements, closed-loop force control, and visual tracking, the system quantified Young's modulus values and viscoelastic parameters of alginate microcapsules, demonstrating an easy-to-operate, accurate compression testing technique for characterizing soft, micrometer-sized biomaterials.
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paper_title: Three-dimensional automated micromanipulation using a nanotip gripper with multi-feedback

paper_content:

In this paper, three-dimensional (3D) automated micromanipulation at the scale of several micrometers using a nanotip gripper with multi-feedback is presented. The gripper is constructed from protrudent tips of two individually actuated atomic force microscope cantilevers; each cantilever is equipped with an optical lever. A manipulation protocol allows these two cantilevers to form a gripper to pick and place micro-objects without adhesive-force obstacles in air. For grasping, amplitude feedback from the dithering cantilever with its normal resonant frequency is used to search a grasping point by laterally scanning the side of the microspheres. Real-time force sensing is available for monitoring the whole pick-and-place process with pick-up, transport and release steps. For trajectory planning, an algorithm based on the shortest path solution is used to obtained 3D micropatterns with high levels of efficiency. In experiments, 20 microspheres with diameters from 3 µm to 4 µm were manipulated and 5 3D micropyramids with two layers were built. Three-dimensional micromanipulation and microassembly at the scale of several microns to the submicron scale could become feasible through the newly developed 3D micromanipulation system with a nanotip gripper.
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paper_title: Vision-based force measurement

paper_content:

This paper demonstrates a method to visually measure the force distribution applied to a linearly elastic object using the contour data in an image. The force measurement is accomplished by making use of the result from linear elasticity that the displacement field of the contour of a linearly elastic object is sufficient to completely recover the force distribution applied to the object. This result leads naturally to a deformable template matching approach where the template is deformed according to the governing equations of linear elasticity. An energy minimization method is used to match the template to the contour data in the image. This technique of visually measuring forces we refer to as vision-based force measurement (VBFM). VBFM has the potential to increase the robustness and reliability of micromanipulation and biomanipulation tasks where force sensing is essential for success. The effectiveness of VBFM is demonstrated for both a microcantilever beam and a microgripper. A sensor resolution of less than +/-3 nN for the microcantilever and +/-3 mN for the microgripper was achieved using VBFM. Performance optimizations for the energy minimization problem are also discussed that make this algorithm feasible for real-time applications.
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paper_title: Force Sensing and Control in Micromanipulation

paper_content:

In micromanipulation, the size of the manipulated object is usually much less than 1 mm in a single dimension, in which case gravitational and inertial forces are no longer dominant. This leads to problems (for manipulation through force) that are not evident in the macroworld, and for which the macroworld techniques alone may not be adequate to provide solutions. This paper surveys critical issues and their available solutions related to force control in micromanipulation. It focuses on: 1) techniques for dealing with adhesion forces and 2) methods for force sensing and control
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paper_title: Improvement of Strain Gauges Microforces Measurement using Kalman Optimal Filtering

paper_content:

Manipulation of small components and assembly of microsystems require force measurement. In the microworld (the world of very small components), signal/noise ratio is very low due to the weak amplitude of the signals. To be used in feedback control or in a micromanipulation system, a force sensor must allow static and dynamic measurements. In this paper, we present a micro-force measurement system based on the use of strain gauges and a Kalman optimal filter. Using a model of the measurement system and a statistical description of the noise, the optimal filter allows filtering the noise without loss of dynamic measurement. The performances of the measurement system are improved and fast force variations can be measured.
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paper_title: PI force control of a microgripper for assembling biomedical microdevices

paper_content:

Recent work is presented on the control of a microgripper based on flexure joints, fabricated by LIGA and instrumented with force sensors. The force sensors are semiconductor strain gauges which have been integrated in the microgripper and experimentally characterised. The microgripper is the core component of a workstation developed to grasp and manipulate tiny objects, such as components of biomedical microdevices. A proportional integral (PI) force control of the microgripper has been implemented. The results of the tracking experiments prove that this control algorithm can assure performance suitable for the intended applications.
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paper_title: Force feedback-based microinstrument for measuring tissue properties and pulse in microsurgery

paper_content:

Miniaturized and "smart" instruments capable of characterizing the mechanical properties of tiny biological tissues are needed for research in biology, physiology and biomechanics, and can find very important clinical applications for diagnostics and minimally invasive surgery (MIS). We are developing a set of robotic microinstruments designed to augment the performance of the surgeon during MIS. These microtools are intended to restore (or even enhance) the finger palpation capabilities that the surgeon exploits to characterize tissue hardness and to measure pulsating vessels in traditional surgery, but that are substantially reduced in MIS. The paper describes the main features and the performance of a prototype miniature robotic instrument consisting of a microfabricated microgripper, instrumented with semiconductor strain-gauges as force sensors. For the (in vitro) experiments reported in the paper, the microgripper is mounted on a workstation and teleoperated. A haptic interface provides force feedback to the operator. We have demonstrated that the system can discriminate tiny skin samples based on their different elastic properties, and feel microvessels based on pulsating fluid flowing through them.
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paper_title: Integrated microendeffector for micromanipulation

paper_content:

Micromanipulation is needed for assembly and maintenance of micromachines and their parts. If the handled objects are miniaturized, interactive forces, such as the van der Waals force, surface tension force, and electrostatic force between microobjects and gripper surface become dominant in the air, and they act as adhesive forces. We cannot neglect such adhesive forces in micromanipulation. Considering the physical phenomena in the microworld, we propose reduction methods for adhesive forces. Surface roughness of the endeffector surface is effective to reduce the van der Waals force. We propose making the micropyramids on the endeffector surface by micromachining techniques. We designed and made a prototype of the microgripper with a microendeffector, the gripping surface of which is formed to have several micropyramids. Experimental results show effectiveness of the micropyramids for reduction of the adhesive force. We also made a semiconductor strain gauge at the end of the microendeffector for grasping force measurement. Both micropyramids and integrated piezoresistive force sensor are fabricated on the microendeffector by the micromachining techniques. Performance of this force sensor is shown.
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paper_title: Towards a force-controlled microgripper for assembling biomedical microdevices

paper_content:

This paper presents recent results on the development and control of a microgripper based on flexure joints, fabricated by LIGA and instrumented with semiconductor strain-gauge force sensors. The microgripper is the end-effector of a workstation developed to grasp and manipulate tiny objects such as the components of a typical biomedical microdevice. The development of the force control in the microgripper is of fundamental importance in order to achieve the dexterity and sensing capabilities required to perform assembly tasks for biomedical microdevices. As a step towards the definition of the force control strategy, system identification techniques have been used to model the microgripper. Results indicate that a proportional integral (PI) controller could be used to assure, at the same time, closed-loop stability of the system, and a bandwidth suitable for the intended applications. The force control is based on strain-gauge sensors which have been integrated in the microgripper and experimentally characterized. Sensor response in the idling condition and during grasp showed that they can provide useful information for force control of the microgripper.
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paper_title: A flexure-based gripper for small-scale manipulation

paper_content:

A small-scale flexure-based gripper was designed for manipulation tasks requiring precision position and force control. The gripper is actuated by a piezoelectric ceramic stack actuator and utilizes strain gages to measure both the gripping force and displacement. The position and force bandwidths were designed for ten Hertz and one hundred Hertz, respectively, in order to afford human-based teleoperative transparency. The gripper serves effectively as a one degree-of-freedom investigation of compliant mechanism design for position and force controlled micromanipulation. Data is presented that characterizes the microgripper performance under both pure position and pure force control, followed by a discussion of the attributes and limitations of flexure-based design.
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paper_title: Vision-based force measurement

paper_content:

This paper demonstrates a method to visually measure the force distribution applied to a linearly elastic object using the contour data in an image. The force measurement is accomplished by making use of the result from linear elasticity that the displacement field of the contour of a linearly elastic object is sufficient to completely recover the force distribution applied to the object. This result leads naturally to a deformable template matching approach where the template is deformed according to the governing equations of linear elasticity. An energy minimization method is used to match the template to the contour data in the image. This technique of visually measuring forces we refer to as vision-based force measurement (VBFM). VBFM has the potential to increase the robustness and reliability of micromanipulation and biomanipulation tasks where force sensing is essential for success. The effectiveness of VBFM is demonstrated for both a microcantilever beam and a microgripper. A sensor resolution of less than +/-3 nN for the microcantilever and +/-3 mN for the microgripper was achieved using VBFM. Performance optimizations for the energy minimization problem are also discussed that make this algorithm feasible for real-time applications.
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paper_title: The effect of material properties and gripping force on micrograsping

paper_content:

This paper presents our work in developing a force controlled microgripper and micrograsping strategies using optical beam deflection techniques. The optical beam deflection sensor is based on modified atomic force microscopy techniques and is able to resolve forces below a nano-Newton. A variety of gripper fingers made from materials with different conductivity and surface roughness is analyzed theoretically and experimentally using the force sensor. These results provide insight into the mechanics of micromanipulation, and the results are used to develop micrograsping strategies. A design of a microfabricated force controlled microgripper is presented along with initial experimental results in applying various gripping forces to microparts. The results demonstrate the important role gripping force plays in the grasping and releasing of microparts.
---
paper_title: Vision-based sensing of forces in elastic objects

paper_content:

Abstract A minimally intrusive, vision-based, computational force sensor for elastically deformable objects is proposed in this paper. Estimating forces from the visually measured displacements is straightforward in the case of the linear problem of small displacements, but not in the case of the large displacements where geometric non-linearities must be taken into account. From the images of the object taken before and after the deformation, we compute the deformation gradients and logarithmic strains. Using the stress–strain relationships for the material, we compute the Cauchy’s stresses and from this we estimate the locations and magnitudes of the external forces that caused the deformation. A sensitivity analysis is performed to examine the effect of small deviations in the experimentally captured displacements on the estimated external forces. This analysis showed that the small-strain case is more sensitive and prone to numerical errors than the large-strain case. Additionally, a related method that is indirect and iterative is also presented in which we assume that we know the locations of the external forces. Numerical and experimental studies are presented for both micro- and macro-scale objects. The main conclusion of this work is that the vision-based force estimation is viable if the displacements of the deforming object can be captured accurately.
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paper_title: Current integration force and displacement self-sensing method for cantilevered piezoelectric actuators

paper_content:

This paper presents a new method of self-sensing both of the displacement and the external applied force at the tip of piezoelectric cantilevers. Integrated electric current across piezoelectric actuators is compensated against material nonlinearities (creep, hysteresis) to provide reliable information. We propose to compensate the hysteresis by using the Prandtl-Ishlinskii static approach while an auto regressive and moving average exogenous (ARMAX) model is used to minimize the creep influence. The quasistatic estimation, electronic circuit, and aspects related to long-term charge preservations are described or referenced. As an experiment, we tested the actuator entering in contact with a fixed force sensor. An input signal of 20 V peak-to-peak (10% of maximum range) led to force self-sensing errors inferior to +/-8%. A final discussion about method accuracy and its limitations is made.
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paper_title: Towards a force-controlled microgripper for assembling biomedical microdevices

paper_content:

This paper presents recent results on the development and control of a microgripper based on flexure joints, fabricated by LIGA and instrumented with semiconductor strain-gauge force sensors. The microgripper is the end-effector of a workstation developed to grasp and manipulate tiny objects such as the components of a typical biomedical microdevice. The development of the force control in the microgripper is of fundamental importance in order to achieve the dexterity and sensing capabilities required to perform assembly tasks for biomedical microdevices. As a step towards the definition of the force control strategy, system identification techniques have been used to model the microgripper. Results indicate that a proportional integral (PI) controller could be used to assure, at the same time, closed-loop stability of the system, and a bandwidth suitable for the intended applications. The force control is based on strain-gauge sensors which have been integrated in the microgripper and experimentally characterized. Sensor response in the idling condition and during grasp showed that they can provide useful information for force control of the microgripper.
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paper_title: Automatic dextrous microhandling based on a 6-DOF microgripper

paper_content:

The demand for automatic quality inspection of individual micro-components has increased strongly in the micro-optoelectronics industry. In many cases, quality inspection of those micro-components needs dexterous microhandling. However, automatic dexterous handling of microcomponents is a very challenging issue which is barely explored. This paper presents a high-DOF (degrees of freedom) automatic dexterous handling and inspection system for micro-optoelectronic components using a novel 6-DOF piezoelectric microgripper. The control system includes three hierarchical layers: an actuator control layer, a motion planning layer and a mission control layer. Machine vision is applied in automatic manipulation. The performance of the system is demonstrated in a vision-based automatic inspection task for 300 × 300 × 100- μ m-sized optoelectronics components and reached a cycle time of 7.1 ± 0.3 s.
---
paper_title: Development of a tactile low-cost microgripper with integrated force sensor

paper_content:

This paper describes recent results of the development of a novel tactile force-sensing microgripper based on a flexure hinge fabricated in stainless steel by wired electro discharge machining (EDM). The gripper was equipped with a commercial semiconductor strain-gauge and a piezo stack. The microgripper is an end-effector of a microrobot developed to grasp and manipulate tiny objects. Acquiring force-information with the microgripper is of fundamental importance in order to achieve the dexterity and sensing capabilities required to perform micromanipulation or assembly tasks.
---
paper_title: Development of a piezoelectric polymer-based sensorized microgripper for microassembly and micromanipulation

paper_content:

This paper presents the design, fabrication, and calibration of a piezoelectric polymer-based sensorized microgripper. Electro discharge machining technology is employed to fabricate the superelastic alloy-based microgripper. It was experimentally tested to show the improvement of mechanical performance. For integration of force sensor in the microgripper, the sensor design based on the piezoelectric polymer PVDF film and fabrication process are presented. The calibration and performance test of the force sensor-integrated microgripper are experimentally carried out. The force sensor-integrated microgripper is applied to fine alignment tasks of micro opto-electrical components. Experimental results show that it can successfully provide force feedback to the operator through the haptic device and play a main role in preventing damage of assembly parts by adjusting the teaching command.
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paper_title: Manipulation at the NanoNewton level: Micrograpsing for mechanical characterization of biomaterials

paper_content:

This paper presents the use of a monolithic, force-feedback MEMS (microelectomechanical systems) microgripper for characterizing both elastic and viscoelastic properties of highly deformable hydrogel microcapsules (15–25µm) at wet state during micromanipulation. The single-chip microgripper integrates an electrothermal microactuator and two capacitive force sensors, one for contact detection (force resolution: 38.5nN) and the other for gripping force measurements (force resolution: 19.9nN). Through nanoNewton force measurements, closed-loop force control, and visual tracking, the system quantified Young's modulus values and viscoelastic parameters of alginate microcapsules, demonstrating an easy-to-operate, accurate compression testing technique for characterizing soft, micrometer-sized biomaterials.
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paper_title: Design, simulation and testing of electrostatic SOI MUMPs based microgripper integrated with capacitive contact sensor

paper_content:

Abstract In this paper a detailed modeling, simulations and testing of a novel electrostatically actuated microgripper integrated with capacitive contact sensor is presented. Microgripper is actuated with lateral comb drive system and transverse comb system is used to sense contact between micro-object and microgripper jaws. The design is optimized in standard SOI-MUMPs micromachining process using L-Edit of MEMS-Pro. Finite element analysis of microgripper is performed in COVENTOR-WARE which shows total displacement of 15.5 μm at the tip of jaws when voltage of 50 Vdc is applied at the actuator. Finite element analysis of sensor part is performed and results are compared with analytical model. Modal analysis is performed to investigate mode shapes and natural frequencies of the microgripper. Microgripper is tested experimentally and total displacement of 17 μm is achieved at the tip of microgripper. The slight difference between finite element analysis and experimental results is due to small variations in the material properties, deposited during the fabrication process. The change in capacitance of capacitive contact sensor is linearly calibrated with the change in the displacement. The sensitivity of contact sensor is 90 fF/μm. The total size of microgripper is 5.03 mm × 6.5 mm.
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paper_title: Monolithically Integrated Two-Axis Microtensile Tester for the Mechanical Characterization of Microscopic Samples

paper_content:

This paper describes the first monolithically integrated two-axis microtensile tester and its application to the automated stiffness measurement of single epidermal plant cells. The tensile tester consists of a two-axis electrostatic actuator with integrated capacitive position sensors and a two-axis capacitive microforce sensor. It is fabricated using a bulk silicon microfabrication process. The actuation range is +/-16 m along both axes with a position resolution of 20 nm. The force sensor is capable of measuring forces up to +/-60 N with a resolution down to 60 nN. The position-feedback sensors as well as the force sensor are calibrated by direct comparison with reference standards. A complete uncertainty analysis through the entire calibration chain based on the Monte Carlo method is presented. The functionality of the tensile tester is demonstrated by the automated stiffness measurement of the elongated cells in plant hairs (trichomes) as a function of their size. This enables a quantitative understanding and a model-based simulation of plant growth based on actual measurement data.
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paper_title: Design of a Micro-Gripper and an Ultrasonic Manipulator for Handling Micron Sized Objects

paper_content:

This work reports on a system consisting of a MEMS (microelectromechanical system) gripper and an ultrasonic manipulator. The gripper is electrostatically actuated and includes an integrated force sensor measuring the gripping force. The device is monolithically fabricated using a silicon-on-insulator (SOI) fabrication process. The resolution of the force sensor is in the sub-micronewton range and, therefore, provides feedback of the forces that dominate the micromanipulation processes. A MEMS ultrasonic device is described which aligns small objects such as biological cells prior to manipulation with the gripper. The concept is demonstrated with polymer spheres, glass spheres and Hela cancer cells, thus providing a useful tool in micro-robotics and biological research.
---
paper_title: Automatic dextrous microhandling based on a 6-DOF microgripper

paper_content:

The demand for automatic quality inspection of individual micro-components has increased strongly in the micro-optoelectronics industry. In many cases, quality inspection of those micro-components needs dexterous microhandling. However, automatic dexterous handling of microcomponents is a very challenging issue which is barely explored. This paper presents a high-DOF (degrees of freedom) automatic dexterous handling and inspection system for micro-optoelectronic components using a novel 6-DOF piezoelectric microgripper. The control system includes three hierarchical layers: an actuator control layer, a motion planning layer and a mission control layer. Machine vision is applied in automatic manipulation. The performance of the system is demonstrated in a vision-based automatic inspection task for 300 × 300 × 100- μ m-sized optoelectronics components and reached a cycle time of 7.1 ± 0.3 s.
---
paper_title: Development of a tactile low-cost microgripper with integrated force sensor

paper_content:

This paper describes recent results of the development of a novel tactile force-sensing microgripper based on a flexure hinge fabricated in stainless steel by wired electro discharge machining (EDM). The gripper was equipped with a commercial semiconductor strain-gauge and a piezo stack. The microgripper is an end-effector of a microrobot developed to grasp and manipulate tiny objects. Acquiring force-information with the microgripper is of fundamental importance in order to achieve the dexterity and sensing capabilities required to perform micromanipulation or assembly tasks.
---
paper_title: Noise characterization in millimeter sized micromanipulation systems

paper_content:

Abstract Efficient and dexterous manipulation of very small (micrometer and millimeter sized) objects require the use of high precision micromanipulation systems. The accuracy of the positioning is nevertheless limited by the noise due to vibrations of the end effectors making it difficult to achieve precise micrometer and nanometer displacements to grip small objects. The purpose of this paper is to analyze the sources of noise and to take it into account in dynamic models of micromanipulation systems. Environmental noise is studied considering the following sources of noise: ground motion and acoustic noises. Each source of noise is characterized in different environmental conditions and a separate description of their effects is investigated on micromanipulation systems using millimeter sized cantilevers as end effectors. Then, using the finite difference method (FDM), a dynamic model taking into account studied noises is used. Ground motion is described as a disturbance transmitted by the clamping to the tip of the cantilever and acoustic noises as external uniform and orthogonal waves. For model validation, an experimental setup including cantilevers of different lengths is designed and a high resolution laser interferometer is used for vibration measurements. Results show that the model allows a physical interpretation about the sources of noise and vibrations in millimeter sized micromanipulation systems leading to new perspectives for high positioning accuracy in robotics micromanipulation through active noise control.
---
paper_title: Monolithically Integrated Two-Axis Microtensile Tester for the Mechanical Characterization of Microscopic Samples

paper_content:

This paper describes the first monolithically integrated two-axis microtensile tester and its application to the automated stiffness measurement of single epidermal plant cells. The tensile tester consists of a two-axis electrostatic actuator with integrated capacitive position sensors and a two-axis capacitive microforce sensor. It is fabricated using a bulk silicon microfabrication process. The actuation range is +/-16 m along both axes with a position resolution of 20 nm. The force sensor is capable of measuring forces up to +/-60 N with a resolution down to 60 nN. The position-feedback sensors as well as the force sensor are calibrated by direct comparison with reference standards. A complete uncertainty analysis through the entire calibration chain based on the Monte Carlo method is presented. The functionality of the tensile tester is demonstrated by the automated stiffness measurement of the elongated cells in plant hairs (trichomes) as a function of their size. This enables a quantitative understanding and a model-based simulation of plant growth based on actual measurement data.
---
paper_title: The effect of material properties and gripping force on micrograsping

paper_content:

This paper presents our work in developing a force controlled microgripper and micrograsping strategies using optical beam deflection techniques. The optical beam deflection sensor is based on modified atomic force microscopy techniques and is able to resolve forces below a nano-Newton. A variety of gripper fingers made from materials with different conductivity and surface roughness is analyzed theoretically and experimentally using the force sensor. These results provide insight into the mechanics of micromanipulation, and the results are used to develop micrograsping strategies. A design of a microfabricated force controlled microgripper is presented along with initial experimental results in applying various gripping forces to microparts. The results demonstrate the important role gripping force plays in the grasping and releasing of microparts.
---
paper_title: Development of a tactile low-cost microgripper with integrated force sensor

paper_content:

This paper describes recent results of the development of a novel tactile force-sensing microgripper based on a flexure hinge fabricated in stainless steel by wired electro discharge machining (EDM). The gripper was equipped with a commercial semiconductor strain-gauge and a piezo stack. The microgripper is an end-effector of a microrobot developed to grasp and manipulate tiny objects. Acquiring force-information with the microgripper is of fundamental importance in order to achieve the dexterity and sensing capabilities required to perform micromanipulation or assembly tasks.
---
paper_title: Noise characterization in millimeter sized micromanipulation systems

paper_content:

Abstract Efficient and dexterous manipulation of very small (micrometer and millimeter sized) objects require the use of high precision micromanipulation systems. The accuracy of the positioning is nevertheless limited by the noise due to vibrations of the end effectors making it difficult to achieve precise micrometer and nanometer displacements to grip small objects. The purpose of this paper is to analyze the sources of noise and to take it into account in dynamic models of micromanipulation systems. Environmental noise is studied considering the following sources of noise: ground motion and acoustic noises. Each source of noise is characterized in different environmental conditions and a separate description of their effects is investigated on micromanipulation systems using millimeter sized cantilevers as end effectors. Then, using the finite difference method (FDM), a dynamic model taking into account studied noises is used. Ground motion is described as a disturbance transmitted by the clamping to the tip of the cantilever and acoustic noises as external uniform and orthogonal waves. For model validation, an experimental setup including cantilevers of different lengths is designed and a high resolution laser interferometer is used for vibration measurements. Results show that the model allows a physical interpretation about the sources of noise and vibrations in millimeter sized micromanipulation systems leading to new perspectives for high positioning accuracy in robotics micromanipulation through active noise control.
---
paper_title: Modeling the trajectory of a microparticle in a dielectrophoresis device

paper_content:

Micro- and nanoparticles can be trapped by a nonuniform electric field through the effect of the dielectrophoretic principle. Dielectrophoresis (DEP) is used to separate, manipulate, and detect microparticles in several domains, such as in biological or carbon nanotube manipulations. Current methods to simulate the trajectory of microparticles under a DEP force field are based on finite element model (FEM), which requires new simulations when electrode potential is changed, or on analytic equations limited to very simple geometries. In this paper, we propose a hybrid method, between analytic and numeric calculations and able to simulate complex geometries and to easily change the electrode potential along the trajectory. A small number of FEM simulations are used to create a database, which enables online calculation of the object trajectory as a function of electrode potentials.
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paper_title: Fusing force and vision feedback for micromanipulation

paper_content:

We present experimental results that investigate the integration of two disparate sensing modalities, force and vision, for sensor-based microassembly. By integrating these sensing modes, we are able to provide feedback in a task-oriented frame of reference over a broad range of motion with an extremely high precision. An optical microscope is used to provide visual feedback down to micron resolutions. We have developed an optical beam deflection sensor to provide nanonewton level force feedback or nanometric level position feedback. The value of integrating these two disparate sensing modalities is demonstrated during controlled micropart impact experiments. Using force feedback alone to control micropart contact transitions, impact forces of over 140 nN were generated before the desired contact force of 2 nN was achieved. When visual servoing is integrated with the force control framework, micropart impact forces of only 9 nN and final contact forces of 2 nN were easily achieved.
---
paper_title: The effect of material properties and gripping force on micrograsping

paper_content:

This paper presents our work in developing a force controlled microgripper and micrograsping strategies using optical beam deflection techniques. The optical beam deflection sensor is based on modified atomic force microscopy techniques and is able to resolve forces below a nano-Newton. A variety of gripper fingers made from materials with different conductivity and surface roughness is analyzed theoretically and experimentally using the force sensor. These results provide insight into the mechanics of micromanipulation, and the results are used to develop micrograsping strategies. A design of a microfabricated force controlled microgripper is presented along with initial experimental results in applying various gripping forces to microparts. The results demonstrate the important role gripping force plays in the grasping and releasing of microparts.
---
paper_title: Automatic dextrous microhandling based on a 6-DOF microgripper

paper_content:

The demand for automatic quality inspection of individual micro-components has increased strongly in the micro-optoelectronics industry. In many cases, quality inspection of those micro-components needs dexterous microhandling. However, automatic dexterous handling of microcomponents is a very challenging issue which is barely explored. This paper presents a high-DOF (degrees of freedom) automatic dexterous handling and inspection system for micro-optoelectronic components using a novel 6-DOF piezoelectric microgripper. The control system includes three hierarchical layers: an actuator control layer, a motion planning layer and a mission control layer. Machine vision is applied in automatic manipulation. The performance of the system is demonstrated in a vision-based automatic inspection task for 300 × 300 × 100- μ m-sized optoelectronics components and reached a cycle time of 7.1 ± 0.3 s.
---

Title: An Overview on Gripping Force Measurement at the Micro and Nano-Scales Using Two-Fingered Microrobotic Systems

Section 1: Introduction
Description 1: Introduce the topic of microrobotics and the importance of gripping force measurement at micro and nano scales using two-fingered microrobotic systems.

Section 2: Force measurement
Description 2: Discuss the range of gripping forces required for different applications and the importance of force measurement in microrobotics.

Section 3: Piezoresistive force sensors
Description 3: Explain the principle, advantages, and limitations of piezoresistive force sensors used in microrobotic applications.

Section 4: Piezoelectric force sensors
Description 4: Describe the piezoelectric force sensors, their working principle, and their suitability for dynamic force measurements.

Section 5: Capacitive force sensors
Description 5: Detail the capacitive force sensors, their construction, and the benefits they offer over other types of sensors.

Section 6: Optical force sensors
Description 6: Cover the use of optical force sensors in microrobotics, including the advantages and challenges associated with these sensors.

Section 7: Force measurement by vision
Description 7: Discuss the techniques of force measurement by vision, its high-resolution capabilities, and its applications in microrobotic manipulation tasks.

Section 8: Discussion about force sensor resolution
Description 8: Provide a discussion on the resolutions of different force sensors and the impact of environmental factors on these resolutions.

Section 9: Two-fingered micromanipulation systems and force measurement at the micro-scale
Description 9: Present a chronological overview of the development and application of two-fingered micromanipulation systems with embedded force sensors.

Section 10: From 1992: the extensive use of strain gauges
Description 10: Summarize early developments in microrobotics focusing on the use of strain gauges for force measurement in micromanipulation.

Section 11: From 2000: Toward the measurement of forces at the nano-Newton scale by the use of external measurement systems
Description 11: Explore advancements made in force measurement at the nano-Newton scale through the use of external systems before the development of embedded sensors.

Section 12: From 2003: Toward embedded and high resolution force sensors
Description 12: Discuss the drive towards embedding high-resolution force sensors within microrobots and the associated challenges.

Section 13: From 2006: The use of MEMS-based microgrippers with embedded capacitive force sensors
Description 13: Highlight significant advances made with MEMS-based microgrippers and capacitive force sensors for precise force measurement and control.

Section 14: Discussion
Description 14: Summarize the main characteristics, performance measures, and challenges of gripping force sensors in current microrobotic systems.

Section 15: Conclusion
Description 15: Recap the developments in gripping force measurement technologies and their applications in microrobotics.

Section 16: Future trends
Description 16: Outline potential future directions in the field of gripping force measurement at the micro and nano scales.