Miniature and cost-effective self-powered triboelectric sensing system toward rapid detection of puerarin concentration

The detection of puerarin concentration is an essential capability to study the functional role of the Pueraria root as a natural medicine and dietary source in the treatment of cardiovascular diseases and liver protection. Current methods to detect and measure puerarin concentration, such as ultraviolet–visible spectrophotometry (UV), are bulky, require an external power supply, and are inconvenient to use. Here, we propose a triboelectric puerarin-detecting sensor (TPDS) which is based on liquid–solid contact electrification, in which liquid–solid interactions generate rapid electrical signals in only 0.4 ms to enable real-time detection of puerarin concentration in water droplets. The electrical signal of the TPDS decreases with an increase of puerarin concentration, and the sensitivity of the approach is 520 V·(μg/mL)⁻¹. The TPDS represents a miniature and cost-effective sensor that is 0.2% of the size and 0.01% of the cost of a UV spectrophotometer. Our theoretical analysis verified that the puerarin concentration in droplets can effectively regulate the electronic structure, where higher concentrations of puerarin lead to a narrower energy bandgap, which allows the TPDS to detect puerarin concentration without the need for an external power supply. The TPDS therefore provides a route for the development of a portable and self-powered method to measure the concentration of an active ingredient in droplets through the conversion of natural energy.