A Generalized Tip-Membrane Contact Detection Algorithm for Automated Single Cell Electroporation Using Statistical Process Control

This work presents a fully automated method for detecting the contact between a microcapillary tip and a cell membrane based on a statistical process control (SPC) algorithm known as the double-sided cumulative sum (or "cusum"). By analyzing current measurements obtained through a microcapillary electrode, the proposed goal of this system is to determine when tip-to-membrane (tip-membrane) contact occurs using thin adhered cells (e.g., less than 10 μm) for the purposes of fully automated robotic-assisted, single cell electroporation (SCE) - a powerful method of gene transfection. This SPC algorithm is robust against uncontrollable system parameters such as system noise common in electrode-based systems, nonstationary processes, and variations in the physical parameters of cells. The proposed algorithm was successfully demonstrated on adhered mammal cells as small as 4 μm in thickness and using tip-placement velocities from 1 to 8 μm/s. In addition, a novel method of experimentation is described correlating optical measurements between tip-membrane proximity and changes in i_cct during the tip-placement sequence.