Wired from the inside

One of the latest revolutions at the intersection of medicine and technology are wearable electronics, although still a technology in development, here I want to present you a summary of products already in the pipeline.

For instance, swedish researchers are working on what they call “epidermal electronics”: flexible, biodegradable skin patches full of sensors and designed to measure heart electrical activity, hydration, body temperature and exposure to ultraviolet light, for instance. A version available to consumers under the name BioStamps will soon be available but another idea is using it in hospitals to monitor the vital signs of newborn babies withouth intrusive mechanisms.

Other skin sensors are being developed to detect temperature, moisture, pulse and oxygen concentration in the blood; or even to detect changes to blood pressure and therefore determine if there’s increased stiffness in the bloodvessels and risk for cardiovascular disease.

Going deeper into the body generates problems for biosensors, namely they should be non-toxic, biocompatible -not generate immune response- and stable enough to function for long periods of time.

Strano’s lab at the MIT has developed detector materials that can be mixed with a water-based gel and injected under the skin. The detector consists of carbon nanotubes coated with polymer strands, whose chemical structure recognizes biomarkers by allowing them to remain docked to them. When biomarkers bind to the polymer, they subtly change the optical properties of the nanotube: shine a light on it, and a glow reveals the presence of the biomarker.

Types of body-electronics. Source: Nature News

Types of body-electronics.
Source: Nature News

So far this biosensor has been used to detect nitric oxide in the blood as an indicator of inflammation, and at least in mice it remained stable for 400 days, the longest for such a type of device, and currently they are working on glucose and cortisol, a stress hormone.

Moreover, similar devices are being developed for organs such as the brain, where a flexible biocompatible epilepsy sensor developed by french scientists has been succesfully tested in human subjects to detect patterns of neuronal firing and could even be used in the future for drug delivery.

Of course, any electronic equipment needs electricity to function and deep in the body having access to it can be a problem since bulky batteries are not an option and changing them can lead to potential infections, therefore new ways of generating electricity in the body have been in demand. One such way is by using static electricity to convert the movement of inhaling/exhaling into energy, enough to move a pacemaker, for instance. This technology is already being tested in pigs after being succesfully used in rats. For devices that do not need such long lived energy sources, another lab has developed a biodegradable battery with electrodes of magnesium and other metals that are safe in low concentrations and which will slowly dissolve in the body.

Withouth a doubt this technology raises concerns, on the one hand it is still not clear what’s the clinical implication of the read out of biomarkers, and on the other hand there are ethical issues that deal with data protection and privacy. On this matter, one possible solution would be that the data would be locked into a body intranet in such a way that the only possibility to transfer data from the biosensors to another device would be by physical interaction using the water molecules of the body as a wire. This is a solution already implemented by the swedish group although yet unpublished.

Certainly there is still a long way to go to make biosensors a reality in the medical praxis but definitely a field to keep an eye on given the great advance it’s shown in the last few years and the potential it implies.

Nature. 2015 Dec 3;528(7580):26-8. doi: 10.1038/528026a. The inside story on wearable electronics. Gibney E.