Biodegradable, Implantable Brain Sensor

Devices designed for implantation in the brain have been used in the treatment of epilepsy and movement disorders for over 10 years. Primarily electrical stimulators, the surgically placed apparatus have been useful as a mechanism of therapeutic treatment for electrical dysfunction in the brain. These electrical stimulators are generally battery operated and have adjustable features for titrating electrical stimulation rate and voltage. So far, implantable devices have been predominantly used to manage conditions rooted in electrical dysfunction of the brain. 

Managing traumatic brain injury as well as other neurological emergencies that cause dangerous intracerebral edema and erratic fluctuations in intracranial physiology presents several challenges, one of which is accurate, well-timed, and safe monitoring of the conditions of the brain and cerebrospinal fluid. The main cornerstone of stroke management and traumatic brain injury management lies in closely analyzing systemic vital signs and vigilantly monitoring the condition of the brain to meticulously adjust blood pressure, body temperature, electrolyte and fluid concentrations, and intracranial pressure.

Frequent invasive methods of obtaining data can be disruptive for the patient's delicate neurological status, while at the same time leaving gaps in data collection and monitoring. Implantable devices can provide more frequent or continuous real time measurements, but, unlike devices that are designed for the long-term treatment of epilepsy or movement disorders, implantable devices for monitoring intracerebral conditions are not intended to remain in the brain for the long term. If surgically placed apparatus remain in the brain, they may create an opportunity for bacterial infections to flourish. Removal of devices presents a physically demanding situation for patients who are already neurologically unstable while recovering from brain injury. 

An interesting new self-degrading implantable device may offer solutions to some of these challenges. Temperature, intracranial pressure, fluid movement, and pH are among the different measures that may be monitored using a newly developed absorbable monitoring device.

Researchers from the University of Illinois and Washington University School of Medicine in St. Louis have developed an implantable electronic device made of silicone material. The device is smaller than the devices currently used for intracerebral monitoring, making them more practical. Another significant feature of the new device is that the sensor, the silicone chip, and the wires are all largely made of biodegradable material, for the objective of eliminating the need for surgical extraction and significantly diminishing the risk of infection.

The device is connected to a wireless transmitter and is capable of continuous transmission of data.  So far, the device that has been designed is not completely degradable, but, according to the researchers, it is 85% biodegradable. The device has not yet been tested in humans – initial trials monitored rats and the researchers reported that the data collected using the device was reliable and comparable to data that is collected using devices currently in use. The researchers report that development for human trials could take as little as 4-5 years.

How likely are you to adopt new technology in intracerebral monitoring of traumatic brain injury patients?

Reference: Kang SK, et al. Bioresorbable silicon electronic sensors for the brain. Nature. 2016 Jan 18. [Epub before print]