Banchelli Luca, Todorov Georgi, Stavrov Vladimir, Ganev Borislav, Todorov Todor
Department of Theory of Mechanisms and Machines, Faculty of Industrial Technology, Technical University of Sofia, 1797 Sofia, Bulgaria.
Department of Manufacturing Technology and Systems, Faculty of Industrial Technology, Technical University of Sofia, 1797 Sofia, Bulgaria.
Micromachines (Basel). 2024 Aug 31;15(9):1117. doi: 10.3390/mi15091117.
Piezoresistive microcantilever sensors for the detection of viruses, pathogens, and trace chemical gasses, with appropriate measurement and signal processing methods, can be a powerful instrument with high speed and sensitivity, with in situ and real-time capabilities. This paper discusses a novel method for mass sensing on the order of a few femtograms, using a dual-microcantilever piezoresistive sensor with a vibrating common base. The two microcantilevers have controllably shifted natural frequencies with only one of them being active. Two active piezoresistors are located on the surfaces of each of the two flexures, which are specifically connected in a Wheatstone bridge with two more equivalent passive resistors located on the sensor base. A dedicated experimental system measures the voltages of the two half-bridges and, after determining their amplitude-frequency responses, finds the modulus of their differences. The modified amplitude-frequency response possesses a cusp point which is a function of the natural frequencies of the microcantilevers. The signal processing theory is derived, and experiments are carried out on the temperature variation in the natural frequency of the active microcantilever. Theoretical and experimental data of the temperature-frequency influence and equivalent mass with the same impact are obtained. The results confirm the sensor's applicability for the detection of ultra-small objects, including early diagnosis and prediction in microbiology, for example, for the presence of SARS-CoV-2 virus, other viruses, and pathogens. The versatile nature of the method makes it applicable to other fields such as medicine, chemistry, and ecology.
通过适当的测量和信号处理方法，用于检测病毒、病原体和微量化学气体的压阻式微悬臂梁传感器可以成为一种具有高速和高灵敏度且具备原位和实时检测能力的强大仪器。本文讨论了一种使用带有振动公共基座的双微悬臂梁压阻式传感器进行飞克量级质量传感的新方法。两个微悬臂梁的固有频率可控地偏移，其中只有一个是有源的。两个有源压阻器位于两个挠曲部分各自的表面上，它们在惠斯通电桥中与位于传感器基座上的另外两个等效无源电阻器专门连接。一个专用实验系统测量两个半桥的电压，并在确定它们的幅频响应后，求出它们差值的模。修改后的幅频响应具有一个尖点，该尖点是微悬臂梁固有频率的函数。推导了信号处理理论，并对有源微悬臂梁固有频率的温度变化进行了实验。获得了温度 - 频率影响以及等效质量具有相同影响的理论和实验数据。结果证实了该传感器适用于检测超小物体，包括微生物学中的早期诊断和预测，例如检测严重急性呼吸综合征冠状病毒2（SARS-CoV-2）病毒、其他病毒和病原体的存在。该方法的通用性使其适用于医学、化学和生态学等其他领域。
