A thin and flexible sensor was developed for sensing sounds, since it can move with the airflow made by even the softest noises. With the least possible resistance to motion, the sensor addresses issues with accelerometers, microphones, and many other similar sensors. The goal was to create a sensor that only resists gravity. It needs to stay connected to the device, but otherwise needed to move with even the slightest sounds or air movement. Being able to move with the air is how sensors are able to tell when a sound is present and from which direction it is coming.
Two billion capacitive microphones are produced every year, but making them both small and effective comes with some challenges. The new sensor platform provides a way to detect the motion of extremely thin fibers or films by sensing changes in an electric field without the use of a magnet. It hasn't previously been feasible to use capacitive sensing on extremely flexible, thin materials because they've needed to resist electrostatic forces that can either damage them or impede their movement.
The new design allows the thin, flexible sensor — which could be spider silk or any other material just as thin — to swing above two fixed electrodes. Because the sensor is at a 90-degree angle from the electrodes, the electrostatic forces don't affect its movement.
This is a critical part of the design because the sensors need to have a high bias voltage — the voltage required for a device to operate — to be effective since the sensitivity of the sensor increases with a high bias voltage.
This design means that capacitive sensors, like the ones used in smartphones, can be both smaller and more efficient. The design also provides other benefits important in various applications; for example, it has a nearly constant potential energy, but can also return to its equilibrium after large motions.