Implanted Medical Sensors Dissolve to Avoid Surgery

Surgeons in the operating room.

Engineers at the University of Connecticut recently unveiled a prototype of a biodegradable pressure sensor that, once surgically placed, could help doctors monitor chronic disease and internal activity before dissolving harmlessly in a patient's body. The small, flexible sensor is made of materials approved for medical use by the Food and Drug Administration (FDA).

These sensors could prove less intrusive than those that currently require surgical removal. It’s comprised of two layers of piezoelectric Poly-L-lactic Acid (PLLA) film sandwiched between molybdenum electrodes and then encapsulated with layers of polylactic acid. The PLLA emits a small electrical charge when even the most minute pressure is applied. These signals can be captured and transmitted to another device and reviewed by a doctor. The molybdenum and polylactic acid are both common materials used for surgical elements that include bone screws, stents, and hip implants.

One of the project's most significant challenges was getting the biodegradable material to produce an electrical charge, as PLLA doesn't emit an electrical charge under pressure in its natural state. So, it was carefully heated, stretched and cut in ways that allowed it to adopt piezoelectric properties. It was then connected to electronic circuits.

The device was tested on a mouse and provided readings equal to those currently in use, and with no side-effects from the material composition. Potential applications could include monitoring patients with glaucoma, heart disease, brain swelling, or bladder cancer. The device may also offer electrical stimulation capabilities for helping to regenerate tissue.

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