Integrated MEMS/NEMS Resonant Cantilevers for Ultrasensitive Biological Detection

Abstract

Recommended by Michele PenzaThe paper reviews the recent researches implemented in Chinese Academy of Sciences, with achievements on integrated resonant microcantilever sensors. In the resonant cantilevers, the self-sensing elements and resonance exciting elements are both topdown integrated with silicon micromachining techniques. Quite a lot of effort is focused on optimization of the resonance mode and sensing structure for improvement of sensitivity. On the other hand, to enable the micro-cantilevers specifically sensitive to bio/chemical molecules, sensing materials are developed and modified on the cantilever surface with a self-assembled monolayer (SAM) based bottom-up construction and surface functionalization. To improve the selectivity of the sensors and depress environmental noise, multiple and localized surface modifications are developed. The achieved volume production capability and satisfactory detecting resolution to trace-level biological antigen of alpha-fetoprotein (AFP) give the micro-cantilever sensors a great promise for rapid and high-resoluble detection.

Detection of anti-IgG using cantilever-type resonant microstructures vibrating in in-plane flexural modes

“…This simplicity is a major advantage for in-the-field or pointof-care applications. There are several examples of point-ofcare type systems that require additional reagents or require initial wetting of the resonator with the sample solution, followed by drying of the device before measurement [20]. The latter strategy in particular can be problematic because it can leave material residues on the sensor's surface producing inaccurate results.…”

Resonant characteristics of rectangular hammerhead microcantilevers vibrating laterally in viscous liquid media

“…), expose the sensor surface to liquid-phase analytes, which are sorbed by a sensitive layer on the device's surface, and then dry the sensor and remeasure its characteristics in air. 9 This strategy can be problematic in practical applications because a washing step is required which necessitates additional reagents. Additionally, particles can contaminate the device surface during the drying step.…”

Geometrical considerations for the design of liquid-phase biochemical sensors using a cantilever's fundamental in-plane mode

“…Often the chosen sensing strategy is to measure a baseline sensor output in air (i.e., resonant frequency, piezoresistor resistance, etc. ), expose the sensor surface to liquid-phase analytes, which are sorbed by a sensitive layer on the device's surface, and then dry the sensor and remeasure its characteristics in air [9]. This strategy can be problematic in practical applications because a washing step is required which necessitates additional reagents.…”