Can a soft ultra-gel the size of a sesame seed "keep watch" for the nervous system?

Popular Science Times (Intern Wang Yuke) Recently, the international scientific journal Nature published a paper by Chinese researchers titled "Injectable Ultrasonic Sensor for Wireless Monitoring of Intracranial Signals". The researchers said that this technology is expected to directly and accurately monitor the physiological functions of the human brain, which is of great significance for determining the degree of injury, prognosis and avoiding the occurrence of diseases.

The implanted supergel sensor is a soft supergel cube, about the size of a sesame seed. A large diameter needle is needed to implant the tiny sensor into the skull to monitor brain health, which will dissolve automatically after a few weeks. Currently, the sensor has been tested on animals and could one day be minimally invasively implanted in humans to monitor neurological diseases such as brain trauma and epilepsy. It would be a wireless sensor that can monitor conditions in the body without surgery.

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Zang Jianfeng, professor of the School of Integrated Circuits at Huazhong University of Science and Technology and corresponding author of the paper, said that when an external ultrasonic source is applied to the supergel sensor, the channel guides the ultrasonic wave to reflect, and the shape of the supergel sensor will be subtly deformed as conditions such as pressure or temperature in the brain change, which can be seen from the reflected ultrasonic wave. This process does not require wires or electronic devices, and the supergel sensor is like a tiny acoustic mirror that can change its reflection according to the environment.

Experiments showed that when the supergel sensors were injected into the brains of rats and pigs, they measured pressure, temperature and flow rate in nearby blood vessels on par with wired probes traditionally used to monitor brain health. The supergel sensors broke down into relatively harmless water and carbon dioxide within four or five weeks.

Zang Jianfeng said that after the supergel sensor was implanted and degraded, the rats used in the experiment showed almost no brain tissue swelling or immune cell accumulation. Before starting human clinical trials, it is still necessary to conduct long-term tests on large animals to prove that the supergel sensor is reliable and safe.