A research team of the Toyohashi University of Technology has developed a label-free biosensor that overcomes the weakness of conventional MEMS-based biosensors for medical and pharmaceutical applications. Utilizing a Fabry-Perot interferometer, the researchers succeeded in raising the sensor's sensitivity by a factor of 100.
Label-free biosensors are used in many laboratory applications including rapid diagnosis, tailor-made medication, and drug discovery. Label-free MEMS-based sensors detect molecules by measuring the deflection of cantilevers caused by biomolecular adsorption. This approach however suffers from poor sensitivity because of low-conversion efficiency of linear transducing from the mechanical deflection to the readout signal.
The research team around Kazuhiro Takahashi from the Toyohashi University has developed a biosensor based on MEMS Fabry-Perot interferometer integrated with a photodiode which utilizes the non-linear optical transmittance change in the Fabry-Perot interference to enhance the sensitivity. The theoretical minimum detectable surface stress of the proposed sensor was predicted to be -1 µN/m, which is two orders of magnitude greater than that of the conventional MEMS sensor.
The sensor was fabricated using a 4-inch, p-type silicon wafer. The photodiode was integrated into the silicon substrate using ion implantation of phosphorus. Sacrificial polysilicon was isotropically etched to form a freestanding membrane. Amino-methyl-functionalized parylene was coated on the membrane for immobilization of the biomolecules via electrostatic coupling.
The MEMS Fabry–Perot interferometric sensor allows the use of a universal biochemical sensing platform in a label-free manner, the research team claims.
This story originally appeared on EE Times Europe.