Non-surgical tiny brain sensor dissolves within weeks of implantation

Tiny sensors can be injected into the skull with a needle to monitor brain health until they dissolve within a few weeks. These sensors have been tested in animals, and in the future, they may enable minimally invasive, implantable sensors in the human body that can monitor traumatic brain injury and neurological disorders such as epilepsy.

“To my knowledge, this is the first wireless sensor that can monitor conditions inside the body without the need for surgery,” he said. Jules Magda The researcher is from the University of Utah, but was not involved in the study.

The sensor is a soft hydrogel cube about 2 millimeters wide, about the width of a grain of rice. Jiangfeng Zhan Professors from China’s Huazhong University of Science and Technology created structured “metagel” sensors by creating precisely spaced air columns throughout a hydrogel. When an external ultrasound source is aimed at the sensor, the channels guide the ultrasound waves. The shape of the sensor changes subtly in response to changing conditions in the brain, such as pressure or temperature, which can be seen in the reflected ultrasound.

“No wiring or electronics are required,” Zhang says. “It’s as if the metagel acts as a tiny acoustic mirror that changes its reflection depending on the environment.”

Zhang and his colleagues showed that when metagel sensors were injected into the brains of rats and pigs, they could measure pressure, temperature, pH levels, and flow rates in nearby blood vessels. They obtained results comparable to wired probes traditionally used to monitor brain health. Their experiments also found that metagel broke down into relatively harmless components, such as water and carbon dioxide, within four to five weeks.

Injecting the sensor into the brain requires a thick needle, which could still cause pain or discomfort, Magda said, and he noted that researchers also need to make sure the dissolved metagel is non-toxic.

Zhang says that the rats in the study showed little swelling in brain tissue or buildup of immune cells after the sensors were implanted and degraded, but he says that longer-term testing in larger animals is still needed to show that the metagel works reliably and safely before clinical trials in humans can begin.