Flexible Hybrid Electronics (FHE) for robotic skin applications

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Flexible(printable) electronics currently has applications in sensors and energy storage devices but is severely limited by the mismatch between components. Only a few 'systems' were build based on printable electronics, due to the hardship of producing high-performance circuits. On the contrary, the classic silicon electronics enables for high performance but lacks the flexible substrate. Therefore, Flexible Hybrid Electronics can be used to get the best of both worlds. The technology relies on the use of the silicon ICs for a high-performance component of the circuit like signal processing, power management, or computation, while the sensing can be done by large-area, flexible printed electronics. Therefore the proposal is to develop a system for electronic skin, which relies on a large sensing area build-out of flexible electronics, and readout and processing part realized by traditional ICs. The skin would consist of a square array of sensors, which can be read from similarly as LCD screens are refreshed. The main controller would iterate over addresses or sensor cells and connect them to the conditioning circuit. While a flexible array of pressure sensors are available on the market, their price goes in thousands of pounds for even simple systems. Moreover, their resolution is lacking, and they offer only one type of sense. On top of that, the connection between the sensor and conditioning electronics can be easily broken when the sensor is bent or twisted. When printing the sensor part of the system, various types of sensors could be combined, like in the case of human skin. There is a possibility of using both resistive and capacitive sensors for pressure, with resistive sensors giving a fast response, while capacitive sensing giving temperature stability. On top of that, temperature sensors, light, humidity, material stress, and more. Moreover, sensors assessing the structural integrity of the skin could be added. Such a system could be cheaply realized using additive-only processes, which work by applying semiconductor and dielectric layers with a screen-printer. Such processes, with interconnection to classic silicon ICs, are commercially available eg. NextFlex. Open source processes, presented by researchers from Singapore exist, with channel lengths as small 100 um presented.