Title: Soft artificial optical skin for biomedical application

Abstract

The human skin being the largest and most exposed organ in the body provides various essential information including touch, temperature, pressure, vibration, and humidity of the surrounding for smooth and safe functioning of our body. Similarly, artificial soft electronic skin, like human skin, perceives various environmental stimuli by transducing them into an electrical signal. Soft artificial skin capable of sensing touch and pressure is essential in many applications, including social robotics, healthcare, and augmented reality. However, 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 soft artificial optical skin made of a soft and resilient polymer capable of detecting touch, load, and bending with extreme sensitivity to touch and load, 750 times higher than earlier work. The soft artificial optical 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, large numbers, yet cost-effective. The soft artificial optical 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 provides the freedom of stretching to the soft artificial optical skin without considering the disjoints among the sensing nodes. The soft artificial optical skin's operation has been shown using a variety of techniques.