Researchers test tiny implantable wireless sensors that dissolve in the brain

By Jonah Comstock
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Researchers at the University of Illinois at Urbana-Champaign are developing tiny sensors that can monitor temperature and pressure within the skull and then dissolve harmlessly into the cranial fluid. When fully developed, these devices could present a new, safer method for monitoring patients after brain surgery or a traumatic brain injury.

“The ultimate strategy is to have a device that you can place in the brain – or in other organs in the body – that is entirely implanted, intimately connected with the organ you want to monitor and can transmit signals wirelessly to provide information on the health of that organ, allowing doctors to intervene if necessary to prevent bigger problems,” Rory Murphy, a neurosurgeon at Washington University and co-author of the paper published in Nature this week, said in a statement. “After the critical period that you actually want to monitor, it will dissolve away and disappear.” 

The research was led by Professor of Materials Science and Engineering John A. Rogers, who has done a lot of research on stretchable and flexible electronics and also co-founded MC10, a Cambridge-based sensor company where he is also a board member.

This research is important because current methods for monitoring the brain after an accident are invasive and therefore expose the patient to additional risks from infection or hemorrhage. They also limit the patient’s movement and quality of life.

“This is a new class of electronic biomedical implants,” Rogers said in a statement. “These kinds of systems have potential across a range of clinical practices, where therapeutic or monitoring devices are implanted or ingested, perform a sophisticated function, and then resorb harmlessly into the body after their function is no longer necessary.”

The dissolving sensor, which functions for a few weeks before melting away, is smaller than a grain of rice. It can sense pressure levels in the intracranial fluid around the brain as well as temperature, and sends that data to a postage stamp-sized transmitter, implanted under the skin on the back of the head. The transmitter would still need to be removed surgically.

For the paper in Nature, the researchers tested the technology in rats against traditional, more invasive means of monitoring pressure and temperature. They found that the accuracy was comparable.

Before the technology can be used in practice with patients, researchers will need to conduct more trials, including trials with humans. But Rogers believes that in the future the technology will be able to go beyond monitoring and even be used in neural therapies.

“We have established a range of device variations, materials and measurement capabilities for sensing in other clinical contexts,” Rogers said. “In the near future, we believe that it will be possible to embed therapeutic function, such as electrical stimulation or drug delivery, into the same systems while retaining the essential bioresorbable character.”