Tiny Implantable Oxygen Sensor Can Monitor Your Organs Using Ultrasonic Power

A team of engineers from the University of California, Berkeley have created an oxygen sensor with a difference: This teeny-tiny device is designed to be implanted into patients in order to monitor tissue oxygen levels way below skin-level.

"It's very difficult to measure things deep inside the body," Professor Michel Maharbiz explains of the problem he and his team sought to solve. "The device demonstrates how, using ultrasound technology coupled with very clever integrated circuit design, you can create sophisticated implants that go very deep into tissue to take data from organs."

Significantly smaller than the tip of your finger — or, by UC Berkeley's measurement, "smaller than the average ladybug," — the tiny implant takes the form of a compact printed circuit board housing a micro-LED, optical filter, and an oxygen-sensing film, along with an integrated circuit and a crystal. When triggered by an ultrasonic wave, the otherwise-passive device transmits data on tissue oxygenation.

"One potential application of this device is to monitor organ transplants, because in the months after organ transplantation, vascular complications can occur, and these complications may lead to graft dysfunction," says postdoctoral researcher Soner Sonmezoglu, who led the engineering effort to integrate oxygen sensing into the device. "It could be used to measure tumor hypoxia, as well, which can help doctors guide cancer radiation therapy."

"By just changing this platform that we built for the oxygen sensor, you can [also] modify the device to measure, for example, pH, reactive oxygen species, glucose or carbon dioxide. Also, if we could modify the packaging to make it smaller, you could imagine being able to inject into the body with a needle, or through laparoscopic surgery, making the implantation even easier."

"In premature infants, for example, we frequently need to give supplemental oxygen but don’t have a reliable tissue readout of oxygen concentration," co-author Dr. Emin Maltepe, a pediatrician at UCSF, adds of the device's possible use-cases. "Further miniaturized versions of this device could help us better manage oxygen exposure in our preterm infants in the intensive care nursery setting and help minimize some of the negative consequences of excessive oxygen exposure, such as retinopathy of prematurity or chronic lung disease."

The team's work has been published under open-access terms in the journal Nature Biotechnology.