A Novel CMUT-Based Ultrasonic Sensing Approach for Tea Polyphenol Concentration Measurement

The rapid advancement of ultrasound medicine owes much to innovations in ultrasonic sensor technology. Capacitive micromachined ultrasonic transducers (CMUTs) have emerged as a pivotal technology, addressing the limitations of traditional piezoelectric sensors and becoming a major area of research. Although CMUT has been widely applied across various fields, they have not yet been used for detecting tea polyphenol concentration. This study proposes a CMUT-based system for measuring tea polyphenol concentration, applying ultrasound technology to tea polyphenol detection for the first time. Compared to traditional detection methods, this system avoids complex sample preparation, enables high-sensitivity real-time detection, and reduces costs. The system utilizes a set of transducers for ultrasonic transmission and reception, with a temperature sensor for real-time monitoring of the solution temperature. By measuring the ultrasonic signal’s time of flight (TOF), the speed of sound is calculated to determine the tea polyphenol concentration. Results indicate that the system can effectively measure tea polyphenol concentrations under different brewing temperatures and conditions. Through extensive experimentation, a relationship between sound velocity and tea polyphenol concentration at specific temperatures was established, with a maximum relative error of 3.7%. The traditional high-performance liquid chromatography (HPLC) detection error ranges from 1% to 5%, demonstrating that the error of this method falls within an acceptable range. These findings demonstrate the feasibility of using ultrasound for tea polyphenol detection, and with the compact, integrable design of CMUT, this system offers potential for real-time, rapid concentration monitoring in tea production and brewing contexts.