Wireless Brain Sensors – A Breakthrough in Medical Plastics

In the era of modern world, medicals advances are evident everywhere. Recently, a team of doctors, researchers and scientists have collaborated to create an electronic biosensor which can be incorporated inside a brain to measure or determine the pH, temperature, flow rates and pressure of the brain. Moreover, it dissolves when no longer needed without the need of any surgical procedure. It is widely applicable in Neuroscience field as brain trauma and injuries kill around 50,000 people per year in the USA alone. These kinds of injuries often cause the brain to swell, which constricts the flow of blood and oxygen, and can lead to permanent damage. So surgeons need reliable ways of monitoring the pressure inside their patients’ head. Earlier, sensors that existed were usually large, heavy and solid, thus had to be removed once the patient recovered. But bioresorbable wireless brain sensors are light, handy and could be easily inserted inside the brain to monitor intracranial pressure and temperature. Once the implantable device is not needed, it is absorbed by the body, eliminating the need of surgically removing the device.

Neurosurgeons working at Washington University School of Medicine in St. Louis and engineers at the University of Illinois at Urbana-Champaign, Murphy and Rogers’s duo, produced a clinically usable pressure sensor consisting of a polylactic-co-glycolic acid membrane suspended in a frame of silicon and magnesium. The electrical resistance of silicon sensor eventually changes with the pressure of the surrounding fluid that causes membrane to fold or bend. The whole sensor device is further wrapped in watertight polymer which absorbs over a period of time, setting the lifetime of the sensor. Moreover, this technology could be used to monitor activity in any organ system throughout the body and dissolve or degrade when critical period is over.

Electronic devices and their biomedical applications are advancing rapidly. But the major limitation of using any implant is that they may trigger an immune response inside the patient body which leads to infections, chronic inflammation, and erosion of skin or organs. The benefits of new devices are their dissolution over a period of time with negation of surgeries which minimizes the infections and further complications. The materials chosen include very small amounts of things like magnesium and silicon, which are recommended parts of the daily diet. In 2012, these sensors built upon the pioneering work on “transient electronics” conducted by John Rogers and his team at the University of Illinois. They developed bioresorbable electronic devices based on very thin silicon sheets in the 20-nanometer range; water-soluble and biocompatible metals such as magnesium, zinc and titanium used as conducting components; and biologically based polymers that can be engineered to adjust the dissolution rate.

Together with a team of engineers, neurosurgeon at the Washington University School of Medicine, Murphy is developing a better option: a dissolvable pressure sensor. Narrower than the tip of a needle, it can be left in brain to monitor internal brain’s activities before completely dissolving. They just get absorbed in the body.

The patent US9326726B2, titled “Wireless system for epilepsy monitoring and measurement” granted to Yale University ITN Energy Systems Inc., discloses a wireless system for brain monitoring/mapping of neurological-disorder patients, It includes a plurality of electrodes which facilitate accurate measurement for specific periods of time through the use of implanted devices and electrodes. Currently, a secondary implant is wired with a sensor incorporated under the skin in a less vulnerable part of the body to transmit the sensor’ data wirelessly to an external source, while also receiving wireless power. Efforts are being made to dissolve the sensor and its wires completely in a few days, but for now, the secondary implant is only 85 percent degradable.

Below are answers to a few questions posted to us by avid readers:

1. How do the sensors operate electrically?
   The sensors are remotely accessible through wireless connectivity. Advanced wireless brain sensors work on brain-computer interfaces to assist people with severe paralysis. It is an implantable model that is fully rechargeable and transmit real-time neuron signals.
   Source: https://www.pharmiweb.com/press-release/2020-02-25/wireless-brain-sensors-market-latest-advancements-market-outlook-2017-to-2027
2. How is data sent from the brain sensor to an external device, and what external device?
   Brain sensors work on the brain-computer interfaces (BCI system), a computer-based system that acquires, analyzes, and translates them into commands which are relayed to an output device like a speeling program, motorized wheelchair, robotic arms that carry out the desired function.
   Sources: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3497935/
   https://www.researchgate.net/publication/3246267_Sensors_for_brain-computer_interfaces  
3. How does the device measure inter-cranial pressure and temperature?
   Percutaneous wiring system adsorbed with biodegradable polymer connect the sensors to the wireless transmission system on the top of the skull. Measurement of intracranial pressure & temperature were recorded with these biodegradable sensors.
   Source: https://www.researchgate.net/publication/290786954_Bioresorbable_silicon_electronic_sensors_for_the_brain
4. How does this collect and store data? Are there any concerns with storing, security, or privacy of data?
   Measurement of intracranial pressure & temperature is done wirelessly with bioabsorbable sensors, which are connected with externally mounted potentiostat transmitters for data transmission through percutaneous wiring. No concerns have come up as yet related to the storage and privacy of patient’s data, allowing doctors to resolve or prevent more significant problems. As this area becomes more lucrative, security measures will keep getting stronger.
   Source: https://engineering.purdue.edu/BioNanoTronics/assets/nature16492.pdf