Surface stress sensor based on MEMS Fabry–Perot interferometer with high wavelength selectivity for label-free biosensing

Abstract

We have developed a surface stress sensor based on a microelectromechanical Fabry–Perot interferometer with high wavelength selectivity by using Au half-mirrors, for highly sensitive label-free biosensing. When the target molecule is adsorbed by the antigen–antibody reaction onto a movable membrane with a thin Au film, which acts as an upper mirror of the optical interferometer, the amount of deflection of the movable membrane deflected by the change in surface stress can be detected with high sensitivity. To improve the signal at the small membrane deflection region of this biosensor resulting in detection of low concentration molecules, by integrating 50 nm-thick Au half-mirrors, the wavelength selectivity of the optical interferometer has been successfully improved 6.6 times. Furthermore, the peak shift in the reflection spectrum due to the adsorption of bovine serum albumin (BSA) antigen with a concentration of 10 ng ml−l by the antigen–antibody reaction was spectroscopically measured on the fabricated optical interferometer, and the deflection amount of the movable membrane after 10 min treatment was 2.4 times larger than that of nonspecific adsorption with the avidin molecules. This result indicated that the proposed sensor can be used for selective detection of low-concentration target antigen molecules.

Label-Free Optical Resonator-Based Biosensors

“…The simple structure of the FPI allows it to be easily combined with a microfluidic system and integrated with other optical materials or components such as a porous silicon or an optical fiber [ 35 , 36 , 37 , 38 ]. FPI-based biosensors boast a high sensitivity compared to other interferometric biosensors based on Mach-Zehnder and Michelson interferometers due to its resonance characteristic through a large number of reflections [ 39 , 40 ].…”

“…There have been efforts to develop optical biosensors utilizing the simple structure of FPI to have characteristics such as an easy fabrication process, simple test setup, and cost-effectiveness [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ]. For example, You et al developed a microfluidic enhanced FPI-based biosensor to detect glucose, sodium chloride (NaCl), and potassium chloride (KCl) for diabetes patients [ 37 ].…”

“…The simplicity of the FPI structure is ideal to develop various configurations by incorporating other structures with it. For example, Takahashi et al utilized an FPI to improve the sensitivity of a microelectrochemical system (MEMS)-based surface stress sensor for label-free biosensing [ 40 ]. The FPI structure consists of two gold (Au) layers with a thickness of 50 nm for highly reflecting surfaces.…”

Piezoresistive Nanomechanical Humidity Sensors Using Internal Stress In-Plane of Si-Polymer Composite Membranes

“…Cantilever-based nanomechanical sensors are increasingly attracting interest as tools for advanced detection of molecules in various fields. Their notable advantages are fast response and highly sensitive real-time and label-free detection ability [1]- [6]. A wide range of applications has been demonstrated using nanomechanical sensors, including process monitoring, disposable medical diagnostic biosensing, and sensing for gases and solvent vapors [7]- [10].…”

A suspended graphene-based optical interferometric surface stress sensor for selective biomolecular detection

“…15,16 We previously developed a surface stress sensor based on optical interferometry to increase stress sensitivity using an optomechanical transducing technique. [17][18][19] For chemical and biomedical sensing, the interface structure of the sensor surface is important. It has been reported that a single molecule of carbon dioxide was detected on suspended graphene.…”