Differential single living cell refractometry using grating resonant cavity with optical trap

Abstract

This letter reports the measurement of single living cell’s refractive index (RI) using the optical grating resonant cavity with buffer modulation on a biochip. The cell’s RI is a significant cell biophysical property which has potential in cancer and disease diagnoses. The single cell is trapped optically within the cavity, and the transmission spectra shift due to the change of surrounding buffer, without/with cell, are used to determine the cell’s effective RI and effective thickness. The measurement shows that Madin-Darby canine kidney cell has an effective RI of 1.383±0.001. Moreover, the optical trapping technique eliminates uncertainty and avoids cell damage.