A nut used in herbal tea has become a hydrogel perfect for a variety of biomedical uses in new research. Scientists created a malva nut hydrogel for medical uses ranging from wound care to ECG readings. The research doesn’t rely on the rumored health benefits of the nuts — in China, they’re known as the sore throat remedy Pangdahai (PDH) — but for their ability to swell 20 times their weight in water.