Wearable reversible based polyoxymethylenmelamine blue 63 methyl stearate thermochromic membrane for temperature sensing

Abstract

The most important indication of health is body temperature, which provides strong motivation for interdisciplinary research to advance measurement methods. In the work conducted, a thermochromic bio-compatible membrane is designed such that it changes color with the rise of temperature to a certain threshold. The novel wearable thermochromic membrane sensor consisted of incorporating polyoxymethylenmelamine blue 63 methyl stearate into a composite matrix of polyvinyl alcohol (PVA) and a water-soluble polyvinylpyrrolidone (PVP). The response is highly colored and varies visibly without any input of electrical power. It turned dark blue at ambient temperatures (20–25 °$C$). At 37–38 °$C$ temperature, its color turns light blue and finally white. Measurements of air permeability and static water contact angles (WCAs) revealed remarkable improvements in comfort and hydrophobic properties. It also improved air permeability from 30.76 to 33.15 cc/sec/cm, and hydrophobicity increased from 4.25°to 52.25°. The membrane flexibilities were found as 2.88 x 10^-3 kg/cm, and tearing force was measured to be 985.91 units, more than the pure PVA/PVP membranes, which stood at 973.12 units, indicating there is greater resistance to tearing under stress. Results in such a membrane have shown very strong thermochromic response, which is suggested by its reflectance measurements of brightness. Then, a thermal detection patch that can be applied directly to the skin has been developed, demonstrating a visibly color-changing response toward such fluctuations of the body’s heat. The results indicate that such a thermochromic patch or membrane will be highly useful for thermal management and early detection of breast cancer.