Flexible, skin-like sensors are a research hotspot worldwide. This is for a number of reasons.
One is that it took billions of years of evolution to create human skin, and the concept of a tough but flexible and highly sensitive covering is one that works. Skin protects us, but also warns us of temperature change, injury, proximity, pressure, and touch, along with dangerous environments, objects, and substances.
Another is that thin, skin-like sensors are lightweight, omnidirectional, could be cheap to manufacture, and may be disposable. All this is preferable to bulky, expensive hardware.
Flexible sensors can be worn by humans in sports, healthcare, fitness, injury recovery, and other monitoring applications. But they can also clad robots and other devices, helping to make them more intuitive for humans to interact with – a concept some may find disturbing.
For example, a new proximity sensor has been developed in the world’s most automated and robot-populated nation (according to International Federation of Robotics statistics), South Korea. The aim is to help collaborative robots, or ‘cobots’, work safely alongside humans.
The flexible, coil-like covering induces electromagnetic fields and measures the changes in resistance that occur when a human approaches within 20-30 centimetres of the device.
Meanwhile, researchers at the University of Toronto in Canada have developed AISkin, a transparent, wearable, and self-powered sensor for monitoring patient health, using two oppositely charged sheets of hydrogel.
Ion movements between the two sheets are generated when the flexible material experiences stresses, humidity, or temperature changes, and these can be measured as electrical signals.
While human skin is stretchable to a degree, the new wearable substance can be stretched up to 400 percent of its length, claim the researchers.
Similarly, researchers at UCLA and the Universities of Waterloo and British Columbia have combined silicone rubber and graphene layers to make 3D printable, wearable sensors that generate electrical signals when moved.
Three years ago, UCLA researchers worked with colleagues at the University of Washington to develop a sensor-filled skin to help robots more safely grasp and manipulate objects.
Also in the US, University of Colorado Boulder researchers have developed an electronic fabric that mimics the properties of human skin, using conductive silver nanoparticles embedded within a covalent plastic.
The beauty industry is also getting in on the act, with multinational brand L’Oreal unveiling a lightweight wearable sensor to warn people of UV exposure and the risk of skin cancer.
- As previously reported on this site, researchers at the Department of Medical Engineering at California Institute of Technology have used laser engraving to help in the mass-production of sensors that are designed to monitor vital signs.
Bodily functions such as sweat can include biomarkers linked to chronic diseases, and these can be picked up by wearable devices.
Researchers used a laser to convert a plastic sheet into a multifunctional wearable surface, which could measure respiration, heart rate, body temperature, and/or biomarkers from sweat.
Image source: Daria Perevezentsev via The University of Toronto
Flexible, skin-like sensors are a research hotspot worldwide. Thin, skin-like sensors are lightweight, omnidirectional, could be cheap to manufacture, and may be disposable
The Time-of-Flight (ToF) sensor market is forecast to grow from a value of $2.8 billion this year to $6.9 billion by 2025. This represents a compound annual growth rate (CAGR) of 20 percent.