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IEEE SENSORS JOURNAL, VOL. 12, NO. 8, AUGUST 2012
2711
Design and Fabrication of Soft Artificial Skin Using Embedded Microchannels and Liquid Conductors
Yong-Lae Park, Member, IEEE, Bor-Rong Chen, Member, IEEE, and Robert J. Wood, Member, IEEE
Abstract— We describe the design, fabrication, and calibration of a highly compliant artificial skin sensor. The sensor consists of multilayered mircochannels in an elastomer matrix filled with a conductive liquid, capable of detecting multiaxis strains and contact pressure. A novel manufacturing method comprised of layered molding and casting processes is demonstrated to fabricate the multilayered soft sensor circuit. Silicone rubber layers with channel patterns, cast with 3-D printed molds, are bonded to create embedded microchannels, and a conductive liquid is injected into the microchannels. The channel dimensions are 200 µm (width) × 300 µm (height). The size of the sensor is 25 mm × 25 mm, and the thickness is approximately 3.5 mm. The prototype is tested with a materials tester and showed linearity in strain sensing and nonlinearity in pressure sensing. The sensor signal is repeatable in both cases. The characteristic modulus of the skin prototype is approximately 63 kPa. The sensor is functional up to strains of approximately 250%. Index Terms— Artificial skin, eutectic gallium indium (EGaIn), pressure sensing, soft sensors, strain sensing.
I. I NTRODUCTION
T
HE DEVELOPMENT of highly deformable artificial skin (Fig. 1) with contact force (or pressure) and strain sensing capabilities [1] is a critical technology to the areas of wearable computing [2], haptic interfaces, and tactile sensing in robotics. With tactile sensing, robots are expected to work more autonomously and be more responsive to unexpected contacts by detecting contact forces during activities such as manipulation and assembly. Application areas include haptics [3], humanoid robotics [4], and medical robotics [5]. Different approaches for
2711
Design and Fabrication of Soft Artificial Skin Using Embedded Microchannels and Liquid Conductors
Yong-Lae Park, Member, IEEE, Bor-Rong Chen, Member, IEEE, and Robert J. Wood, Member, IEEE
Abstract— We describe the design, fabrication, and calibration of a highly compliant artificial skin sensor. The sensor consists of multilayered mircochannels in an elastomer matrix filled with a conductive liquid, capable of detecting multiaxis strains and contact pressure. A novel manufacturing method comprised of layered molding and casting processes is demonstrated to fabricate the multilayered soft sensor circuit. Silicone rubber layers with channel patterns, cast with 3-D printed molds, are bonded to create embedded microchannels, and a conductive liquid is injected into the microchannels. The channel dimensions are 200 µm (width) × 300 µm (height). The size of the sensor is 25 mm × 25 mm, and the thickness is approximately 3.5 mm. The prototype is tested with a materials tester and showed linearity in strain sensing and nonlinearity in pressure sensing. The sensor signal is repeatable in both cases. The characteristic modulus of the skin prototype is approximately 63 kPa. The sensor is functional up to strains of approximately 250%. Index Terms— Artificial skin, eutectic gallium indium (EGaIn), pressure sensing, soft sensors, strain sensing.
I. I NTRODUCTION
T
HE DEVELOPMENT of highly deformable artificial skin (Fig. 1) with contact force (or pressure) and strain sensing capabilities [1] is a critical technology to the areas of wearable computing [2], haptic interfaces, and tactile sensing in robotics. With tactile sensing, robots are expected to work more autonomously and be more responsive to unexpected contacts by detecting contact forces during activities such as manipulation and assembly. Application areas include haptics [3], humanoid robotics [4], and medical robotics [5]. Different approaches for