Soft Tactile Skin Using an Embedded Ionic Liquid and Tomographic Imaging

Whole-body-contact sensing will be crucial in the quest to make robots capable of safe interaction with humans. This paper describes a novel design and a fabrication method of artificial tactile sensing skin for robots. The manufacturing method described in this paper allows easy filling of a complex microchannel network with a liquid conductor (e.g., room temperature ionic liquid (RTIL)). The proposed sensing skin can detect the magnitude and location of surface contacts using electrical impedance tomography (EIT), an imaging technique mostly used in the medical field and examined recently in conjunction with sensors based on a piezoresistive polymer sheet for robotic applications. Unlike piezoresistive polymers, our IL-filled artificial skin changes its impedance in a more predictable manner, since the measured value is determined by a simple function of the microchannel geometry only, rather than complex physical phenomena. As a proof of concept, we demonstrate that our EIT artificial skin can detect surface contacts and graphically show their magnitudes and locations.

[1]  Radhika Nagpal,et al.  Design and control of a bio-inspired soft wearable robotic device for ankle–foot rehabilitation , 2014, Bioinspiration & biomimetics.

[2]  N. Hu,et al.  Tunneling effect in a polymer/carbon nanotube nanocompositestrain sensor , 2008 .

[3]  Carmel Majidi,et al.  3D structures of liquid-phase GaIn alloy embedded in PDMS with freeze casting. , 2013, Lab on a chip.

[4]  Vladimir J. Lumelsky,et al.  Development of sensitive skin for a 3D robot arm operating in an uncertain environment , 1989, Proceedings, 1989 International Conference on Robotics and Automation.

[5]  Pierre Lambert.  Surface Tension in Microsystems: Engineering Below the Capillary Length , 2013 .

[6]  R. Wood,et al.  A non-differential elastomer curvature sensor for softer-than-skin electronics , 2011 .

[7]  T. Ding,et al.  Changes in electrical resistance of carbon‐black‐filled silicone rubber composite during compression , 2007 .

[8]  Mari Velonaki,et al.  Improved Image Reconstruction for an EIT-Based Sensitive Skin With Multiple Internal Electrodes , 2011, IEEE Transactions on Robotics.

[9]  Tzu-Jen Kao,et al.  A 3D reconstruction algorithm for EIT using a handheld probe for breast cancer detection , 2006, Physiological measurement.

[10]  Zongchang Zhao,et al.  Thermodynamic properties of a new working pair: 1-Ethyl-3-methylimidazolium ethylsulfate and water , 2010 .

[11]  Ahmed Elsanadedy,et al.  Application of Electrical Impedance Tomography to Robotic Tactile Sensing , 2012 .

[12]  Takao Someya,et al.  A large-area, flexible pressure sensor matrix with organic field-effect transistors for artificial skin applications. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[13]  Yong-Lae Park,et al.  A Soft Strain Sensor Based on Ionic and Metal Liquids , 2013, IEEE Sensors Journal.

[14]  Yasuo Kuniyoshi,et al.  A deformable and deformation sensitive tactile distribution sensor , 2007, 2007 IEEE International Conference on Robotics and Biomimetics (ROBIO).

[15]  Y. Kato,et al.  Tactile Sensor without Wire and Sensing Element in the Tactile Region Based on EIT Method , 2007, 2007 IEEE Sensors.

[16]  Yong-Lae Park,et al.  Design and Fabrication of Soft Artificial Skin Using Embedded Microchannels and Liquid Conductors , 2012, IEEE Sensors Journal.

[17]  C. J. Kotre,et al.  EIT image reconstruction using sensitivity weighted filtered backprojection. , 1994, Physiological measurement.

[18]  Clément Gosselin,et al.  A flexible robot skin for safe physical human robot interaction , 2009, 2009 IEEE International Conference on Robotics and Automation.

[19]  Rebecca K. Kramer,et al.  Hyperelastic pressure sensing with a liquid-embedded elastomer , 2010 .

[20]  Ruben D. Ponce Wong,et al.  Sensors and Actuators A: Physical , 2022 .

[21]  Mark R. Cutkosky,et al.  A robust, low-cost and low-noise artificial skin for human-friendly robots , 2010, 2010 IEEE International Conference on Robotics and Automation.

[22]  David Rye,et al.  Improved EIT drive patterns for a robotics sensitive skin , 2009 .

[23]  D. Geselowitz.  An application of electrocardiographic lead theory to impedance plethysmography. , 1971, IEEE transactions on bio-medical engineering.

[24]  Carmel Majidi,et al.  Liquid-phase gallium-indium alloy electronics with microcontact printing. , 2013, Langmuir : the ACS journal of surfaces and colloids.

[25]  Isao Shimoyama,et al.  Stretchable liquid tactile sensor for robot-joints , 2010, 2010 IEEE International Conference on Robotics and Automation.

[26]  Xingmei Lu,et al.  A new theory for ionic liquids—the Interstice Model , 2004 .

[27]  Clément Gosselin,et al.  Characterization of the electrical resistance of carbon-black-filled silicone: Application to a flexible and stretchable robot skin , 2010, 2010 IEEE International Conference on Robotics and Automation.

[28]  M. Shimojo,et al.  A tactile sensor sheet using pressure conductive rubber with electrical-wires stitched method , 2004, IEEE Sensors Journal.

[29]  G. Whitesides,et al.  Eutectic Gallium‐Indium (EGaIn): A Liquid Metal Alloy for the Formation of Stable Structures in Microchannels at Room Temperature , 2008 .

[30]  Yun Zhu,et al.  A Novel Ionic-Liquid Strain Sensor for Large-Strain Applications , 2009, IEEE Electron Device Letters.

[31]  C. Kim,et al.  Electrowetting and electrowetting-on-dielectric for microscale liquid handling , 2002 .

[32]  M. Narkis,et al.  Quantitative model relating electrical resistance, strain, and time for carbon black loaded silicone rubber , 1994 .

[33]  K. Marsh,et al.  Room temperature ionic liquids and their mixtures—a review , 2004 .

[34]  Robert J. Wood,et al.  Influence of cross-sectional geometry on the sensitivity and hysteresis of liquid-phase electronic pressure sensors , 2012 .

[35]  William R B Lionheart,et al.  Uses and abuses of EIDORS: an extensible software base for EIT , 2006, Physiological measurement.

[36]  L M Heikkinen,et al.  A MATLAB package for the EIDORS project to reconstruct two-dimensional EIT images. , 2001, Physiological measurement.

[37]  Giulio Sandini,et al.  An embedded artificial skin for humanoid robots , 2008, 2008 IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems.

[38]  Oussama Khatib,et al.  Springer Handbook of Robotics , 2007, Springer Handbooks.

[39]  Huang Ying,et al.  Research on Nano-SiO2/Carbon Black Composite for Flexible Tactile Sensing , 2007, 2007 International Conference on Information Acquisition.

[40]  Daniel M. Vogt,et al.  Design and Characterization of a Soft Multi-Axis Force Sensor Using Embedded Microfluidic Channels , 2013, IEEE Sensors Journal.

[41]  Robin D. Rogers,et al.  Ionic Liquids: Science and Applications , 2012 .

[42]  Mark R. Cutkosky,et al.  Dynamic Tactile Sensing , 2014, The Human Hand as an Inspiration for Robot Hand Development.

[43]  J Dargahi,et al.  Human tactile perception as a standard for artificial tactile sensing—a review , 2004, The international journal of medical robotics + computer assisted surgery : MRCAS.

[44]  V. Lumelsky,et al.  Sensitive skin , 2000, IEEE Sensors Journal.

[45]  Robert J. Wood,et al.  Wearable tactile keypad with stretchable artificial skin , 2011, 2011 IEEE International Conference on Robotics and Automation.

[46]  Benjamin C. K. Tee,et al.  Skin-like pressure and strain sensors based on transparent elastic films of carbon nanotubes. , 2011, Nature nanotechnology.

[47]  Y. Fouillet,et al.  Ionic liquid droplet as e-microreactor. , 2006, Analytical chemistry.