Design and test of reliable high strength ingressive polycrystalline silicon microgripper arrays

We present the design and validation of a micromachined gripper array that enables reliable transmission of forces of at least 14 mN. The gripper is constructed with polycrystalline silicon (polysilicon), a brittle material, and is compatible with polysilicon surface micromachining. Two ingressive snap-and-lock array designs are presented. After developing design guidelines, it is shown that the first gripper array is functional. However, a risk remains that the gripper array rather than the tensile bar that it grips in its intended application fails. Therefore, an improved geometry is designed and it is shown that it is robust with respect to failure. Scanning confocal Raman imaging directly confirms that the local peak tensile stresses in the robust gripper array are approximately 50% of the lower bound material strength, and also resolves a 25% stress variation across the array.

[1]  R. Muller,et al.  Silicon-processed overhanging microgripper , 1992 .

[2]  R. L. Edwards,et al.  A new technique for measuring the mechanical properties of thin films , 1997 .

[3]  O. Tabata,et al.  Specimen size effect on tensile strength of surface-micromachined polycrystalline silicon thin films , 1998 .

[4]  S. Johansson,et al.  Mechanical characterization of thick polysilicon films: Young's modulus and fracture strength evaluated with microstructures , 1999 .

[5]  Silvestro Micera,et al.  Towards a force-controlled microgripper for assembling biomedical microdevices , 2000 .

[6]  J. Sniegowski,et al.  IC-Compatible Polysilicon Surface Micromachining , 2000 .

[7]  Brian D. Jensen,et al.  Interferometry of actuated microcantilevers to determine material properties and test structure nonidealities in MEMS , 2001 .

[8]  Ivo W. Rangelow,et al.  Electrostatically driven microgripper , 2002 .

[9]  H. Kang,et al.  Development of a piezoelectric polymer-based sensorized microgripper for microassembly and micromanipulation , 2004 .

[10]  L. Freund,et al.  Thin Film Materials: Stress, Defect Formation and Surface Evolution , 2004 .

[11]  Stephane Regnier,et al.  Electrostatic actuated micro gripper using an amplification mechanism , 2004 .

[12]  W. Cleghorn,et al.  Microassembly of 3-D microstructures using a compliant, passive microgripper , 2004, Journal of Microelectromechanical Systems.

[13]  Byung Kyu Kim,et al.  Institute of Physics Publishing Smart Materials and Structures a Superelastic Alloy Microgripper with Embedded Electromagnetic Actuators and Piezoelectric Force Sensors: a Numerical and Experimental Study , 2022 .

[14]  Norman A. Fleck,et al.  Comparison of microtweezers based on three lateral thermal actuator configurations , 2005 .

[15]  Ole Hansen,et al.  Electro-thermally actuated microgrippers with integrated force-feedback , 2005 .

[16]  Hyeun-Seok Choi,et al.  The development of a microgripper with a perturbation-based configuration design method , 2005 .

[17]  Yen-Wen Lu,et al.  Microhand for biological applications , 2006 .

[18]  Ioannis Chasiotis,et al.  Fracture Toughness and Subcritical Crack Growth in Polycrystalline Silicon , 2006 .

[19]  Ivo W. Rangelow,et al.  Thermally driven microgripper as a tool for micro assembly , 2006 .

[20]  Larry L. Howell,et al.  Simulation, measurement, and asymmetric buckling of thermal microactuators , 2006 .

[21]  B. Nelson,et al.  Monolithically Fabricated Microgripper With Integrated Force Sensor for Manipulating Microobjects and Biological Cells Aligned in an Ultrasonic Field , 2007, Journal of Microelectromechanical Systems.

[22]  Gareth J. Monkman,et al.  Impactive Mechanical Grippers , 2007 .

[23]  David Wood,et al.  Design and testing of a polymeric microgripper for cell manipulation , 2007 .

[24]  M. Dugger,et al.  Nanotribology and MEMS , 2007 .

[25]  Yu Sun,et al.  Nanonewton force-controlled manipulation of biological cells using a monolithic MEMS microgripper with two-axis force feedback , 2008 .

[26]  Jiang Zhe,et al.  A Capillary Microgripper based on Electrowetting , 2008 .

[27]  Michael S. Baker,et al.  Demonstration of an in situ on-chip tensile tester , 2009 .

[28]  S. Hazra High throughput, on-chip, in situ investgations of structural properties of polycrystalline silicon for microelectromechanical systems , 2010 .

[29]  B. Boyce A Sequential Tensile Method for Rapid Characterization of Extreme-value Behavior in Microfabricated Materials , 2010 .

[30]  D. Kang,et al.  Specimen alignment in an axial tensile test of thin films using direct imaging and its influence on the mechanical properties of BeCu , 2010 .

[31]  J. W. Foulk,et al.  Predicting Fracture in Micron-Scale Polycrystalline Silicon MEMS Structures , 2010 .

[32]  Yu Sun,et al.  Autonomous Robotic Pick-and-Place of Microobjects , 2010, IEEE Transactions on Robotics.

[33]  Brandon K. Chen,et al.  MEMS microgrippers with thin gripping tips , 2011 .

[34]  J. Beuth,et al.  Compact On-Chip Microtensile Tester With Prehensile Grip Mechanism , 2011, Journal of Microelectromechanical Systems.

[35]  R. Cook,et al.  Stress mapping of micromachined polycrystalline silicon devices via confocal Raman microscopy , 2014 .

[36]  J. Beuth,et al.  Validated Prediction of the Strength Size Effect in Polycrystalline Silicon Using the Three‐Parameter Weibull Function , 2014 .

[37]  Hye Rin Kwag,et al.  Stimuli-responsive theragrippers for chemomechanical controlled release. , 2014, Angewandte Chemie.