Biosensors that are wearable on human skin or safely used inside the body are increasingly prevalent for medical applications and everyday health monitoring. Finding the right materials to bind the sensors together and adhere them to surfaces is also an important part of making this technology better.
Researchers developed a material using polydimethylsiloxane (PDMS) silicone material popular for use in biosensors because of its biocompatibility and soft mechanics. It is generally utilized as a solid-film, nonporous material, which can lead to problems in sensor breathability and sweat evaporation.
One experiment with electrocardiogram (ECG) analysis showed that the porous PDMS allowed for the evaporation of sweat during exercise, capable of maintaining a high-resolution signal. The nonporous PDMS did not provide the ability for the sweat to readily evaporate, leading to a lower signal resolution after exercise. The team created a porous PDMS material through electro-spinning, a production method that makes nanofibers through the use of electric force.
During mechanical testing, the researchers found that this new material acted like the collagen and elastic fibers of the human epidermis. The material was also capable of acting as a dry adhesive for the electronics to strongly laminate on the skin for adhesive-free monitoring. Biocompatibility and viability testing also showed better results after seven days of use, compared to the non-porous PDMS film.
The material can be used in applications where fluids are needed to passively transfer through the material — such as sweat — to readily evaporate through the device. Because the material’s permeable structure is capable of biofluid, small-molecule, and gas diffusion, it can be integrated with soft biological tissue such as skin, neural, and cardiac tissue with reduced inflammation at the application site.
Among the applications are electronics for healing long-term, chronic wounds; breathable electronics for oxygen and carbon dioxide respiratory monitoring; devices that integrate human cells within implantable electronic devices; and real-time, in-vitro chemical and biological monitoring.