Image credit: Chuangian Shi/University of Colorado Boulder
Skin is the largest organ in the human body and the most exposed. Not only can it touch and feel objects, it is resilient, stretchy, and self-healing. Scientists and engineers have been working on synthetic versions, dubbed electronic skin or e-skin, to address multiple practical applications, and technology is making it possible.
In its most basic form, electronic skin is a flexible patch containing sensors and wireless communication capabilities. It can be used to measure vital signs, track physical movement, and provide sensation to artificial or robotic body components.
Synthetic but Sustainable
Researchers at the University of Colorado Boulder have developed self-healing electronic skin that can track the wearer’s heart rate, body temperature, and daily step count. The flexible synthetic skin is slightly thicker than a Band-Aid and can be applied to skin anywhere on the body using heat.
The device is produced using a screen-printing process that creates a network of liquid metal wires that make up the circuit. It is sandwiched between two thin sheets of polyimine, a self-healing material. The process also allows the e-skin to stretch in any direction between 30 and 60 percent without damaging the electronics inside. Even if cut, the electronic skin can repair itself in 13 minutes simply by pinching the cut together.
The UC Boulder team developed the e-skin and sensors with sustainability in mind. When it is no longer needed, the device can be placed in a methanol solution that dissolves the skin and allows the chips and circuitry to be repurposed. The electronic skin is still in the test phase as researchers work to overcome some hurdles, most notably that the electronic skin requires an external power source to operate.
The Pressure Is On
Stanford University researchers have developed an e-skin that detects applied pressure. Microscopic capacitors and pressure sensors can measure multi-directional forces, and a slightly domed design with miniscule molded pyramids increases its sensitivity. The e-skin has been tested on a robotic arm and could be used to give prosthetic limbs tactile capabilities.
Researchers at RMIT University in Melbourne, Australia, have created electronic skin that senses pressure, pain, and heat. Artificial skin receptors can react to thresholds for heat and pain, similar to the way nerves send signals to the human brain. The electronic skin uses stretchable electronics in a thin, transparent silicone film that adheres to the body like a sticker. It includes temperature-reactive coatings to respond to heat, and electronic memory cells to mimic the brain’s ability to recall and react to previous stimuli, including pain.
The research team claims that its electronic skin can react to real pressure, temperature, and pain and differentiate between a gentle poke and a more forceful pinprick. In the future the technology can be used to design smart prosthetics and more intelligent robotics. It can also be applied to skin grafts.
Electronic skin also holds the potential to monitor healing and deliver drugs to patients. Researchers at the University of Illinois are developing e-skin that monitors skin temperature and hydration to quantify wound healing. Even from a remote office, doctors eventually will be able to track factors that could indicate infection.
Image credit: RMIT University
Other e-skin products can monitor biometric changes and dispense drugs if needed. One prototype uses strain gauges to detect tremors and can trigger heating elements to release drugs stored in nanoparticles. The device contains memory cells to record the activity for later review. Another skin-like device monitors smokers and can be programmed to release nicotine to curb cravings before they light up.
As IoT technologies further enable telemedicine initiatives, electronic skin will help medical professionals improve remote patient care, enhance prosthetics, and advance intelligent robotics.
- Find out more about e-skin developments from University of Colorado Boulder.
- Learn more about Stanford University’s wearable technologies.
- Discover what RMIT University’s Micro Nano Research Facility is developing.