Subblescope: Novel Thin-Film Haptic Sensing Using a Single-Bubble Approach

Abstract

Vision-based haptic sensors have become increasingly prevalent for tactile feedback in robotic fingers, allowing rough and precise interactions with objects. Subblescope, a soft, affordable vision-based tactile sensor, records interactive surface dynamics. A monolayer EcoFlex with a stable air bubble makes up the sensor. A camera records the bubble’s deformation to normal and shear forces calibrated by a micro-UTM, while an LED array illuminates the elastomer. In normal loading, the sensor has a sensitivity of 248.6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>N, a repeatability of 1.09% at 0.6 N, and a hysteresis of 26.23 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>J between 0.1 and 0.6 N. For shear loading, the range is 0.02–0.15 N, with a sensitivity of 31.31 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>N, bettering existing vision-based haptic sensors in resolution and sensitivity. The simulation in COMSOL examines how indentation shape, size, and placement affect the sensor. The current design is compliant to detect bidirectional force exchanges on interactive surfaces. Multiple bubbles can be populated in the elastomer for further study toward spatiotemporal sensing to detect tactile cues, such as friction, hardness, and texture.