Medical sensors are often implanted in directly into soft tissues and organs of a patient’s body. A surgical operation is required to remove the sensor when it is no longer needed or functional, introducing risks of infection and extending the patient’s recovery time. Researchers at Ucon (University of Connecticut, USA) set out to develop a biodegradable solution to this problem.

They came up with a biodegradable pressure sensor made of medically safe materials. The sensor relies on the piezoelectric effect to produce an electrical charge when it is compressed. To achieve this effect the researchers had to transform a medically safe but electrically neutral polymer into a piezoelectric material by altering its internal molecular structure.

A biodegradable sandwich

The resulting sensor consists of two layers of piezoelectric film sandwiched between tiny molybdenum electrodes and encapsulated with layers of polylactic acid. A prototype was implanted in the abdomen of a mouse in order to monitor the mouse’s respiratory rate. It emitted reliable readings of contractions in the mouse’s diaphragm for four days before breaking down into its individual organic components.

The sensor is very sensitive and responds to very slight pressures. Its signal can be captured and transmitted to another device for monitoring and reviewing. The device could also be used to provide electrical stimulation for tissue regeneration. Other potential applications include monitoring patients with glaucoma, heart disease, and bladder cancer.

(Image courtesy of Thanh Duc Nguyen)