Nobody likes being awkwardly poked by a cold pair of rubber gloves at the doctors’, but if it saved your life you wouldn’t complain. And while scientists haven’t found a way to make such diagnostic prodding sessions more bearable, they could have made developments that might mean they yield more valuable information.
Described in Nature Nanotechnology, Japanese and U.S. researchers headed by Professor Takao Someya from the University of Tokyo have come up with a new pressure-sensing material that’s not only wafer-thin and resistant to deformation, but also maintains accuracy even when bent in a variety of ways. If this novel sensor could be incorporated into examination gloves, then it could possibly aid cancer diagnosis by helping doctors feel tumors.
To create the material, scientists first had to work out a way to overcome a major stumbling block in the development of pressure sensors for medical monitoring. Although flexible sensors have been developed before, it’s challenging to come up with devices that can take accurate measurements while being mechanically deformed, such as during twisting or wrinkling. And that’s not ideal if the tissue being studied is soft and stretchy, like the skin, or if the surface subject is complex and constantly in motion, which unfortunately is the case for most of our tissues.
So what they did was create pressure-sensitive nanofibers constructed of a combination of microscopic tubes made from carbon and one-atom-thick sheets of carbon called graphene. Ranging from a tiny 300 to 700 nanometers in diameter, layers of these composite fibers were then randomly tangled up and stacked to generate a highly transparent, spongy structure. After adding in transistors – tiny devices that switch or amplify signals – and layering these with the fibers on strong, heat-resistant polymers called polyimides, the team tested out their material in a range of situations.
Even when deformed, the device can measure pressure distribution remarkably accurately. Credit: 2016 Someya Laboratory
Impressively, thanks to the ability of the nanofibers to change their alignment during deformation, the strain on the fibers caused by bending was significantly reduced. This meant that it maintained sensitivity and accuracy even when warped over a bump as tiny as 80 micrometers, roughly twice the thickness of a strand of hair. They also tested it out on an artificial heart system, which showed that it was capable of detecting pressure changes that would be useful in blood pressure monitoring.
Since certain cancers (such as breast cancer) are monitored using light pressure applied by hands and fingers, the researchers think that materials like this could become a useful tool in the clinic. Broader than that, the resistance to distortion could make it a useful material for the field of wearable electronics, where vital information can be continually measured and monitored for extended periods of time.