Automated Force Curve Methods Based Micropipette Force Sensors

Abstract

Force curve is the most important techniques for accurate measuring the stiffness, adhesion and energy dissipation. However, due to the challenges of probe-cell localization, this type of single-cell analysis tool has become a labor-intensive and time-consuming procedure. Here, we demonstrate an automatic positioning methods based on micropipette for force curves acquisition. The automation covers the detection of cells in label-free images, pre-positioning and automatic focusing of micropipette, as well as automated force curves. This new method discards silicon-based probes used in traditional AFM, and instead utilizing a transparent micropipette with an unobstructed tip as the sensor. This advancement enables accurate localization of the probe tip and cell under an optical microscope. Furthermore, during the probe positioning process, we have implemented a pre-localization method using focused laser projection. This allows for manual adjustment of the probe tip within a range of 70 micrometers, providing precise region of interests (ROI) for automatic tip focusing. Combining with the aforementioned techniques. We also demonstrate the high-precision localization and force curve acquisition of eight fixed cells on a single image. The measurement results indicate that the positioning error will not exceed 3.4 μm. Our work has effectively enhanced the efficiency of cellular mechanical measurements and holds the potential to achieve automated high-throughput single-cell analysis and drug screening.