Micro- and nanomechanical sensors for environmental, chemical, and biological detection

Abstract

Micro- and nanoelectromechanical systems, including cantilevers and other small scale structures, have been studied for sensor applications. Accurate sensing of gaseous or aqueous environments, chemical vapors, and biomolecules have been demonstrated using a variety of these devices that undergo static deflections or shifts in resonant frequency upon analyte binding. In particular, biological detection of viruses, antigens, DNA, and other proteins is of great interest. While the majority of currently used detection schemes are reliant on biomarkers, such as fluorescent labels, time, effort, and chemical activity could be saved by developing an ultrasensitive method of label-free mass detection. Micro- and nanoscale sensors have been effectively applied as label-free detectors. In the following, we review the technologies and recent developments in the field of micro- and nanoelectromechanical sensors with particular emphasis on their application as biological sensors and recent work towards integrating these sensors in microfluidic systems.

Liquid-Phase Chemical Sensing Using Lateral Mode Resonant Cantilevers

“…The mass sensitivity of a resonator can be increased by reducing the resonator mass and increasing its frequency, 9 i.e., simply by scaling down the dimensions in the case of a cantilever. In contrast, the gravimetric sensitivity also considers the scaling of the volume of the sensitive layer with changing resonator dimensions.…”

Sensor Arrays Based on Polycyclic Aromatic Hydrocarbons: Chemiresistors versus Quartz-Crystal Microbalance

“…[1][2][3][4][5] These arrays could meet the growing demand for rapid and flexible online detection of a wide range of chemical and biological agents in different branches of industry, homeland security, 5,6 environmental monitoring, 5,7,8 and medical diagnostics [1][2][3][4][5][9][10][11][12][13][14][15][16][17][18][19][20] . Combined with statistical algorithms, these sensor arrays can provide convenient bionics of the mammalian olfactory system for identifying complex gas samples, without the necessity of identifying their separate ingredients.…”

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

“…Two reasons for this are: (1) viscous damping can severely limit the resolution of cantilevers operated in liquid and (2) when operated in the traditionally utilized fundamental out-of-plane flexural mode, there is a significant amount of mass-loading by the surrounding liquid as evidenced by the frequency shift when the devices are immersed in liquid. This leads to a higher starting mass and thus lower mass sensitivity [2] and [3]. In this work, cantilevers utilizing the fundamental in-plane flexural mode are characterized in liquid and the quality factor and frequency shift due to fluid loading are measured.…”