The evolution of next-generation biosensors calls for the integration of miniaturized sensors into microchips, such as microelectromechanical systems (MEMS). Recent progress in nanotechnology, along with innovative approaches to synthesizing nanomaterials and fabricating MEMS devices, has simplified the design and development of advanced sensing strategies and portable devices. MEMS, emerging as pivotal technologies, play an increasingly vital role in a wide range of applications, from classic use like sensing, actuation, and switches in environmental monitoring, smart phones, IoT nodes, robotic servants, and autonomous vehicles to precise quantum sensors. Resonance frequency (f) and quality factor (Q) are two fundamental parameters determining the performance of the MEMS sensors, such as response speed, detectivity, stability, and signal-to-noise ratio. When sensing is based on the frequency shift, Q factor is of paramount importance. However, increasing the resonance frequency always leads to the degradation of the Q factor for the fundamental resonance mode due to increased dissipation in the system. Therefore, the product of f‧Q presents as a figure of merit for MEMS resonators. High f‧Q product is generally desirable to achieve high sensitivity, fast response speed, and enhanced resilience to mechanical noise sources. Diamond has been considered the best candidate for high-performance and high-reliability MEMS sensors in terms of its exceptional mechanical, thermal, and chemical properties. Despite the theoretical f‧Q of diamond in Akhieser regime is lower than Si, the practical Q factor over 1 million at room temperature was achieved, much higher than that of Si. By using diamond cantilevers, the durability of the AFM probe and the reliability of magnetic or mass sensors under extreme conditions can be much improved. We fabricated single-crystal diamond (SCD) cantilevers with the higher-order resonance and the f‧Q at different resonance modes. Remarkably, with little change of the Q factors at the higher-order resonance, the f‧Q product of the SCD increased by over 15 times, for the third order resonance relative to the first order resonance. The progress provides a promising application scene for SCD MEMS cantilevers, such as AFM probes, magnetic/mass sensors. We also performed ion implantation of nitrogen and rare-earth elements; and the introduction and manipulation of nitrogen-vacancy color centres and evaluation by using both Ion implantation facilities and focused ion beam in the UK to produce the high performance devices and sensors. We also developed a novel electrochemical sensor, based on the high-performance characteristics of MOFs with an innovative 3D-printed HMNsAP equipped with a microvalve. Our work integrated the novel strategy to in increase the electrocatalytic activity. Additionally, the developed microvalve could precisely regulate fluid flow when connected to a vacuum tube, enabling efficient and contamination risk-free ISF extraction.
