UConn engineers recently developed a biodegradable pressure sensor. The device is built to monitor a slew of medical conditions, including chronic lung disease and swelling of the brain, before safely dissolving within the patient’s body.
Approved by the U.S. Food and Drug Administration (FDA), the sensor aims to replace current implantable devices that contain potentially toxic materials. Furthermore, existing pressure sensors need to be physically removed, which can lead to complications and a longer road to recovery.
“Medical sensors are often implanted directly into soft tissues and organs,” says Thanh Duc Nguyen, the paper’s senior author and an assistant professor of mechanical and biomedical engineering at the Institute of Materials Science at the Storrs campus and Institute of Regenerative Engineering at UConn Health. “Taking them out can cause additional damage. We knew that if we could develop a sensor that didn’t require surgery to take it out, that would be really significant.”
To test the device, a prototype sensor was implanted into a mouse’s abdomen to monitor its respiratory rate. It provided accurate measurements during a four-day span, and then dissolved.
Researchers also implanted a prototype into the back of a mouse, in order to test if it was medically sound. After monitoring the mouse’s immune system, only minor inflammation was recorded, and all adjacent tissue returned to normal after four weeks.
Creating a piezoelectric effect presented a significant design obstacle. The process consists of the biodegradable material creating an electrical charge when under pressure. Eventually, the team was able to heat, stretch, and cut the materials in a way that produced piezoelectric properties.
When pressure is applied, the sensor emits an electrical charge. Those signals are recorded and transmitted to a different device, which is then reviewed by a doctor.
In a proof-of-concept test involving another mouse patient, the implanted sensor was connected to an external signal amplifier. The amplifier transmitted the signals to an oscilloscope, where the data could be viewed. Results showed equivalent reliability compared to existing commercial devices.
At this time, the team is researching ways to elongate the device’s functional lifetime. Until then, the sensor could help patients avoid additional surgery and assist with many medical conditions.
“There are many applications for this sensor,” says Nguyen. “Let’s say the sensor is implanted in the brain. We can use biodegradable wires and put the accompanying non-degradable electronics far away from the delicate brain tissue, such as under the skin behind the ear, similar to a cochlear implant. Then it would just require a minor treatment to remove the electronics without worrying about the sensor being in direct contact with soft brain tissue.”
Currently, the team has filed for a patent and its application is pending. The full details of the research can be found in the journal Proceedings of the National Academy of Sciences.
