Multi-mode strain and curvature sensors for soft robotic applications

Abstract

In this paper we describe the fabrication and testing of elastomer-based sensors capable of measuring both uniaxial strain and curvature. These sensors were fabricated from Sylgard 184, which is a transparent silicone elastomer. We created microchannels directly in silicone elastomer substrates using a laser to ablate material. The sensing element was an alloy of gallium and indium, which is liquid at room temperature, contained within the laser-created microchannels. As the substrate deformed, the microchannel deformed within it, resulting in a measurable change in electrical resistance. By fabricating two matching resistive strain-sensing elements on opposite sides of the sensor, we were able to unambiguously measure uniaxial strain and curvature by observing the common mode and differential mode changes in resistance, respectively. There was very little coupling between modes, demonstrating the utility of the differential sensor design. We characterized the sensor in terms of its response to strain and curvature, its noise, and its stability over time. We believe that this type of sensor has application in soft sensory skins and can observe pose in soft robotic systems.

Strain sensor-embedded soft pneumatic actuators for extension and bending feedback

“…By embedding a pair of displacement sensors into the SPA, we are able to determine distinctly both extension and bending by calculating the mean and difference of the two sensor measurements, respectively. This approach is similar to that reported by [24], wherein the sum and difference of the values reported from two curvature/strain sensors mounted back-to-back were used to report linear strain and curvature. Using the sSPAs presented here, the extension and bending angle can be determined from two sensor values and the pneumatic pressure applied to the actuators.…”

Flexible Multifunctional Sensors for Wearable and Robotic Applications

“…The accuracy of the sensor could be increased with a larger number of channels, but at the cost of spatial complexity. Edward et al [31] presented their work on a multimode strain and curvature sensors, as shown in Figure 10c. Sensor molds were 3D-printed and the encasing material was Ecoflex since this is one of the most popular encasing materials for making soft and stretchable sensors.…”

“…[161] All phenomena with regard to the origin of color arises from the interaction between electromagnetic waves of light and vibration of electrons in the medium where light passes through. [31] Copyright 2017, Elsevier. On the other hand, when the material has a periodic distribution of refractive index, which is Adv.…”

“…[28] Intrinsic and conductive materials coated conductive fabrics are soft, conformable, and can be readily attached to, or weaved, into clothing. [30,31] To date, such conductive sensors can be stretched to a wide range of strains, from ≈5% to 400%. Liquid metal conductors are soft and can be fabricated into fibers [29] and planar structures.…”

“…Liquid metal conductors are soft and can be fabricated into fibers [29] and planar structures. [30,31] To date, such conductive sensors can be stretched to a wide range of strains, from ≈5% to 400%.…”