Changes in electric potential and impedance of human skin can cause significant errors in biopotential measurements such as electrocardiograms (EKGs) and electroencephalograms (EEGs). To overcome this problem, light abrasion of the skin using fine sandpaper is generally recommended before attaching electrodes. This process can be uncomfortable for patients and adds to the preparation time for the procedure. Improving ionic transport between the electrode and the body could eliminate the need for preparatory skin abrasion. A medical device manufacturer came to Battelle looking for material solutions that would provide fast response and equivalent performance without the need for skin abrasion.
Battelle researchers started with a literature review in order to find the latest research on how the structure and chemical makeup of materials impact ionic transport. This information was used to develop a model for understanding how different variables impact the ability of materials to transport ions across the stratum corneum (the outer layer of skin). Because the final product would involve human contact, we narrowed down potential materials to those that have been generally recognized as safe (GRAS). Using these criteria, we developed a list of potential materials that are safe for human contact, provide rapid penetration of the skin and good electrical contact, and are able to maintain that contact for an extended period of time. After testing several variations, researchers developed a gel mixture that incorporates commercially available GRAS compounds already in common use in the cosmetics industry. The final formulation was optimized through several rounds of testing using human subjects.
The final gel mixture demonstrates high levels of performance for biopotential measurement without skin abrasion, equivalent or better than performance of traditional electrode gels applied after abrasion. It provides fast response and long-lasting connection, making it appropriate for hospital environments where monitoring devices must be attached for extended periods of time. The gel is easy and economical to manufacture using commonly available GRAS materials. It can be added to the surface of the electrode during manufacturing, allowing hospital technicians to simply peel and stick the electrode to exposed skin without preparatory abrasion. Battelle received a patent for the gel and is seeking a partner for IP licensing.