Determination of refractive index for single living cell using integrated biochip

This paper reports a novel method for measuring the effective refractive index (RI) of single living cell with a small integrated chip. This microchip is able to determine the RI of living cell in real time without extra requirements of fluorescence labeling and chemical treatments, offering low cost and high accuracy meanwhile. It might provide an efficient approach for diseases or cancer diagnosis. The measurement system integrates laser diode, microlenses, and microfluidic channels onto a monolithic chip. In the experiments, two standard polystyrene beads with nominal RIs are, employed to calibrate the system and five types of cancerous cells are subsequently measured. The results indicate that the RI of the tested cells ranges from 1.392 to 1.401, which is larger than typical value 1.35-1.37 for normal cells.