Hybrid device: A diagram of the layers in the new soft pressure sensor. (Courtesy: the University of Texas at Austin)
Topics: Applied Physics, Biotechnology, Nanotechnology
Wearable pressure sensors are commonly used in medicine to track vital signs, and in robotics to help mechanical fingers handle delicate objects. Conventional soft capacitive pressure sensors only work at pressures below 3 kPa, however, meaning that something as simple as tight-fitting clothing can hinder their performance. A team of researchers at the University of Texas has now made a hybrid sensor that remains highly sensitive over a much wider range of pressures. The new device could find use in robotics and biomedicine.
The most common types of pressure sensors rely on piezoresistive, piezoelectric, capacitive, and/or optical mechanisms to operate. When such devices are compressed, their electrical resistance, voltage, capacitance, or light transmittance (respectively) changes in a well-characterized way that can be translated into a pressure reading.
The high sensitivity and long-term stability of capacitive pressure sensors make them one of the most popular types, and they are often incorporated into soft, flexible sensors that can be wrapped around curved surfaces. Such sensors are popular in fields such as prosthetics, robotics, and biometrics, where they are used to calibrate the strength of a robot’s grip, monitor pulse rates, and blood pressure, and measure footstep pressure. However, these different applications involve a relatively wide range of pressures: below 1 kPa for robotic electronic skin (e-skin) and pulse monitoring; between 1 and 10 kPa for manipulating objects; and more than 10 kPa for blood pressure and footstep pressure.
Wearable pressure sensors extend their range, Isabelle Dumé, Physics World