MEMS Resonant Mass Sensor With Integrated Optical Manipulation

We investigate optical manipulation of particles in fluid as a viable method to achieve better experimental fidelity and extend the application of integrated-fluidic resonant-mass sensing. Fluctuations in sample position or trajectory can lead to measurement error, thereby degrading the resolution with which these devices can accurately characterize mass. Optical trapping offers precise location control in such fluidic environments and can define and fix position to mitigate variability, but requires a novel approach to design, fabrication, and biological viability concerns. Optical considerations are especially imperative when working with biological cells, organic matter, or other materials adversely affected by imposing high intensity laser light, and mandate the use of a photonic-crystal structure. Given these requirements, this letter details a design and fabrication approach embodied by unique devices that demonstrate compatibility with optical trapping and mass sensing. Accordingly, the effects of optical manipulation on the measurement are disclosed, toward long-term biological mass monitoring and sensing. Ultimately, precise measurement of singular cell mass could answer many fundamental biological questions, with implications in cell biology, pharmacology, and medicine.