Automated method of calibrating drop delay for flow cytometry

HAN Tianhao, WANG Peng, YU Xinglong

（Departmentof Precision Instruments, Tsinghua University, Beijing 100084, China）

Abstract: In order to solve the problem of instability of drop delay in a flow cytometer when the driving pressure changes, a mathematic relationship of jet velocity and the driving pressure was deduced and thereafter a mathematic relation between drop delay and relevant parameters was obtained. The experimental curve of jet velocity and the driving pressure, as well as the relation curves of drop delay and the driving pressure or the piezoelectric signal amplitude were obtained by manual calibration. An experiment of maintaining the drop delay though regulating the piezoelectric signal amplitude according to the driving pressure was conducted as well. A good agreement between the experiment results and the mathematical model was found. The results indicate that, with other conditions unchanged, the drop delay remains stable if the driving pressure and the piezoelectric signal amplitude are kept in certain relationship and it is feasible to maintain the drop delay through monitoring the driving pressure.

Key words: flow cytometry; drop delay; mathematical model; automatic calibration