Interface Charge Transfer Mapping for In Situ Monitoring of Contamination in Liquid Food

Abstract In situ detection of contamination in liquid food production by intelligent sensing equipment in a factory is of great significance to ensure food safety, quality control, process optimization, and cost reduction. Current technologies require samples to be extracted and analyzed using bulky, expensive, and large instruments, which are time‐consuming, complex, and cannot be realized in situ detection. In this work, a high‐density array Triboelectric Nanogenerator (TENG) probe is fabricated by combining triboelectrification and charge transfer at liquid–solid interface, and interface charge transfer mapping (ICTM) is applied to the identification and safety detection of liquid foods. When a liquid food droplet slides across an insulated surface, the electrometer connected with the metal electrode array will record the electric signals, and the electric signals at each electrode will generate an ICTM. The ICTMs are sensitive to the compositions of various liquid food and additives, thus can be used to in situ detect contamination in liquid food production. Ten different liquid foods are successfully identified by ICTMs, as well as food additives and heavy metals in 5° white vinegar. The detection limit of Pb 2+ in 5° white vinegar is as low as 10 µg L −1 (in line with FDA standards), and the linear range is 0–10 µg L −1 . Finally, through the detection of 20 random samples, the detection accuracy of lead acetate in 5° white vinegar is 95%, and the detection accuracy of potassium sorbate is 90%. The array TENG probe and the generated ICTM open an approach for in situ and rapid food production and safety testing relying on cheap, portable, low‐tech instrumentation.