Electronic fingertip enhances surgeons’ sense of touch

A consortium from the University of Illinois at Urbana-Champaign, Northwestern University and Dalian University of Technology has developed a wearable electronic fingertip capable of responding with high precision to the stresses and strains associated with touch and finger movement. The device consists of ultra thin, stretchable, silicon based electronics and soft sensors, and could be a step towards the creation of surgical gloves for use in medical procedures such as local ablations and ultrasound scans. It works by giving the wearer electrotactile stimulation – a tingling sensation caused by a small voltage applied to the skin. The size of the voltage is controlled by the sensor and varies depending on the properties of the object being touched. "Imagine the ability to sense the electrical properties of tissue, and then locally remove that tissue, precisely by local ablation, all via the fingertips using smart surgical gloves," said Professor John Rogers of the University of Illinois at Urbana-Champaign. "Alternatively, or perhaps in addition, ultrasound imaging could be possible." The researchers suggest that the new technology could open up possibilities for surgical robots that can interact, in a soft contacting mode, with their surroundings through touch. The electronic circuit on the 'skin' is made of patterns of gold conductive lines and ultra thin sheets of silicon, integrated onto a flexible polymer called polyimide. The sheet is then etched into an open mesh geometry and transferred to a thin sheet of silicone rubber moulded into the precise shape of a finger. This electronic 'skin', or finger cuff, is designed to measure the stresses and strains at the fingertip by measuring the change in capacitance of pairs of microelectrodes in the circuit. Applied forces decrease the spacing in the skin which, in turn, increases the capacitance. According to the researchers, the fingertip device could also be fitted with sensors for measuring motion and temperature, with small scale heaters as actuators for ablation and other related operations The researchers believe that because the device exploits materials and fabrication techniques adopted from the established semiconductor industry, the processes can be scaled for realistic use at reasonable cost. They now intend to create a 'skin' for integration on other parts of the body, such as the heart. In this case, a device would envelop the entire 3d surface of the heart, like a sock, to provide various sensing and actuating functions, providing advanced surgical and diagnostic devices relevant to cardiac arrhythmias. They are also looking at creating materials and schemes to provide the device with wireless data and power.