Soft electronic skin (soft-e-skin) capable of sensing touch and pressure similar to human skin is essential in many applications, including robotics, healthcare, and augmented reality. However, most of the research effort on soft-e-skin was confined to the lab-scale demonstration. Several hurdles remain challenging, such as highly complex and expensive fabrication processes, instability in long-term use, and difficulty producing large areas and mass production. Here, we present a robust 3D printable large-area electronic skin made of a soft and resilient polymer capable of detecting touch and load, and bending with extreme sensitivity (up to 150 kPa–1) to touch and load, 750 times higher than earlier work. The soft-e-skin shows excellent long-term stability and consistent performance up to almost a year. In addition, we describe a fabrication process capable of producing large areas and in large numbers, yet is cost-effective. The soft-e-skin consists of a uniquely designed optical waveguide and a layer of a soft membrane with an array of soft structures which work as passive sensing nodes. The use of a soft structure gives the liberty of stretching to the soft-e-skin without considering the disjoints among the sensing nodes. We have shown the functioning of the soft-e-skin under various conditions.

We present an on chip optofluidic surface deformable liquid Dove prism (LDP) based low‐fluid flow pressure monitoring device. The unique design of the device in combination with liquid and soft solid enabled by the total internal reflection of light makes the sensor highly sensitive and compatible with the integration of a microfluidic and/or Lab‐on‐a‐chip device. A layer‐by‐layer soft lithographic (LSL) and 3D printing technique are exploited to make the device. We have used Polydimethylsiloxane (PDMS) as the layer material and two variety of liquids (a) immersion oil (IO) and (b) di‐iodomethane (DI) as refracting medium to construct the LDP sensor. Optical ray tracing simulation is performed to optimize the sensor. The pressure sensor shows sensitivity as high as ±28.5 mV per 50 Pa pressure with an error ± 2.5 mV and repeatability of ~99.56% at full scale. We have shown the applicability of the sensor by capturing and analyzing respiratory pressure signals of some human subjects at numerous conditions.

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The relevance of pressure sensors in daily life applications has been phenomenal in diversified disciplines such as engineering, bio-medical, automobile, aerospace etc. Making right choice of pressure sensors is crucial in any of these disciplines. Of late, the pursuit of making the pressure sensors applicable to various domains has spurred a variety of innovative activities. They are being fabricated using novel materials and unconventional fabrication methodology. Also, the advent of microelectromechanical systems has provided new horizons for a variety of realizations that led to the development of efficient and robust pressure sensors. The electromechanical characteristics of the sensing materials and the fabrication methodologies employed to realize the sensor have significant influence on performance of the sensor. This paper reports the micro composite based piezoresistive gauge pressure sensor performance study which was realized by screen printing technique. Graphite-PVC resin based dispersions are screen printed on flat, circular shaped, 1.98 mm thick stainless-steel diaphragm. The transducing layers are directly printed on the deforming polymer coated diaphragm so that the coupling factor is high, resulting in an efficient transfer of strain. Pressure cyclic study and its effect on linearity, hysteresis, sensitivity, stability etc. are investigated. The sensitivity is found to be 0.357 mV/bar. The maximum hysteresis and non-linearity are found to be less than 0.8% FSO. A fairly satisfactory sensitivity, linearity, hysteresis and stability are accomplished at a low cost. By observing the performance characteristics of the realized pressure sensor it can be used in commercial, industrial, automotive, aerospace and strategic fields. Some of the applications could be in tire pressure sensing, air filling in petrol bunks, petrol/diesel/oil/water tankers, water supply pipelines, oil/gas explorations, hydraulic jacks and mines etc.

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