Scientists produce ultrathin and stretchable soft electronics

Researchers from Nanyang Technological University (NTU) have established a pilot laboratory capable of rapid prototyping ultrathin and stretchable electronics that detect bioelectric signals from the skin, muscles and organs, and transmit these signals to control robots or other electronic devices.

By attaching these smart sensors to limbs or the head, users with limb disabilities or mobility impairments can control robotic prosthesis, machinery and motorised wheelchairs using alternative muscle movements and bio-signals. These innovative soft electronics were developed by combining in-house designed soft materials and processes with commercially available hardware components. The hybrid combination allows the researchers to integrate many types of sensor on the market, such as wireless connectivity, accelerometer, temperature sensing, and monitoring of vitals like heart rate, blood pressure, oxygen levels and more.

The resulting sensors, encased in a gel-like skin, are soft, flexible and stretchable, similar to silicon bandages used in health care. The sensors adhere to the skin, enable joint movement, and come in various sizes and thicknesses, ranging from centimetres to sub-microns the width of a human hair.

Conventionally, semiconductor manufacturing produces electronics that rely on silicon as the primary substrate or platform. However, silicon is hard and rigid. Soft electronics, instead, use a soft platform such as hydrogels or biocompatible plastics that are stretchable and flexible. To enable electronic circuits to accommodate movement without breaking under repeated stress, these circuits are printed on soft substrates using intricate patterns at the micro and nanoscale, about 10 times thinner than the width of a human hair.

NTU Professor Chen Xiaodong established the pilot laboratory which aims to co-develop and produce soft electronic devices with industry partners, including small and medium Enterprises (SMEs). “My goal is to establish a new centre of excellence for soft electronics, building a team of industry experts and commercial partners to swiftly bring these technologies to market,” Chen said.

Through joint projects, Chen hopes to establish industry standards to facilitate the mass production of soft electronics in the future and develop the necessary expertise for this industry. Chen’s team recently developed a wavy ribbon form for soft electronics, which will allow them to stretch without breaking. Another one of Chen’s innovations is “BIND” — a soft, stretchy, ‘Lego-like’ universal connector that joins flexible electronics by pressing them together. It can withstand stretching up to seven times its length and is reportedly 60 times tougher than conventional connectors. When used together, these technologies allow conventional hardware chips to be mounted and linked to resistors and capacitors through printed circuits.

Image credit: iStock.com/shawn_hempel