Silicon is cheap — a feature that has made it a darling of the electronics industry. But it has a major problem: It doesn’t play well with people.
“People are the worst enemy of silicon,” said Paul Berger, an electrical and computer engineering professor at Ohio State University. “When we sweat, we sweat sodium and potassium out of our pores. That is the bane of a silicon device.” The electrolytes are common inside the body too, where they perform tasks like regulating fluid content and controlling muscles. Silicon sensors inserted under the skin quickly attract and absorb sodium and potassium, rendering them unreliable.
Berger and his colleagues decided to search for a way to protect silicon from electrolytes. They settled on aluminum oxide, which is used in everything from toothpaste to sandpaper. When a silicon sensor is coated with aluminum oxide, it can last up to 24 hours inside the human body.
The coating’s first application could be a quick 5-to-10 minute diagnostic test that can determine if a transplant recipient is in danger of rejecting an organ. Medical professionals would insert a needle covered in silicon sensors into a patient’s body to sense if proteins that indicate organ stress are present. Then they would do something Berger said is key: throw the needle away. Needles need to be disposable, and silicon can make that affordable.