Skinflow: A soft robotic skin based on fluidic transmission

In this paper we present Skinflow, a novel soft robotic sensor based on liquid transmission. The sensor combines liquid filled soft silicone chambers and optical sensors to measure pressure, bending and vibration. When mechanically stimulated, the volume of the chambers changes and this change is transmitted to a display cell by an incompressible, coloured liquid. The displacement of the liquid in the channels is captured by a CCD camera and is quantified by image processing algorithms. We present three implementations of this concept. The first device is a soft button array with four pressure sensitive buttons. The second implementation is a three-dimensional soft touchpad, that consists of two sensor layers oriented at 90° to each other. Both layers have eight macrochannels that are filled with coloured liquid. The sensor is able to measure the position and the intensity of the touch. Finally, the third device shows how the processing unit for the proposed liquid filled sensors can be integrated using a smart vision camera and a microcontroller. Three soft bend sensors are connected to the processing unit and we control the brightness of three light emitting diodes (LEDs) in realtime by bending them. The presented sensors are safe, low cost and scalable. They can be used in soft robots, smart homes and wearables as well as for medical diagnosis, especially where electronic devices cannot be used due to electromagnetic interference (e.g. magnetic resonance imaging).