An Acoustothermal Heater for Paper Microfluidics towards Point-of-care Glucose Detection

We report the first observation of acoustothermal heating of wet papers under high frequency vibrations. The proposed heating method utilizes acoustic absorption of cellulose fiber, which exhibits viscoelastic properties. The surface acoustic waves propagate on the piezoelectric substrate and refract into a wet paper strip on the substrate. The refracted longitudinal waves deliver acoustic energy into the wet paper by vibration damping in the form of heat. Acoustothermal heating was discovered to be frequency-dependent and to reach local maxima at certain frequencies. Based on this finding, we developed a paper-based microfluidic heating system for point-of-care glucose detection.