Tiny, flexible, and biocompatible implantable sensors that are smaller than a grain of rice have been successfully worn for over four years now by human subjects, as was reported by Profusa, a South San Francisco firm, at the just concluded American Chemical Society’s 254th National Meeting. The wireless and battery-free implants are designed to measure different metabolites, with the current focus mostly on oxygen saturation.
They’re placed near the surface of the body using a syringe and can remain in their position seemingly indefinitely. That’s because they’re made of a biocompatible hydrogel (poly(2-hydroxyethyl methacrylate)) used to manufacture contact lenses and the surface of the sensor is rough to simulate a natural object and to promote cells and tissues to grow onto and around the device.
To make the devices detect analytes, such as glucose or lactate, the implants have fluorescent dyes attached to their surface that glow differently depending on the concentration of the particular analyte in their environment. A device placed near the skin where the sensor is bathes it in infrared light, triggering the fluorescence and measuring its intensity. The device that does this then transmits its readings to a paired computer or cell phone that displays the results and keeps a record of previously captured data.
Profusa’s technology has already received European regulatory approval to measure tissue oxygen levels in patients with peripheral artery disease and work is underway toward FDA’s approvals.
first product has been approved for marketing in Europe and has been shown to report tissue oxygen levels in patients under treatment for peripheral artery disease.
Here’s a scientist from Profusa describing the company’s technology at American Chemical Society’s meeting: