On-chip noncontact actuation of a micro-pipette driven by permanent magnets

We have developed a novel on-chip micro-tool that can act as a pipette. This micro-pipette comprised a pump and nozzle. The pump had a membrane made of a negative photoresist sheet. The membrane was pumped by permanent magnets, and a cell was aspirated and fixed at the tip of the nozzle. The thickness of the membrane was designed with the help of FEM analysis results. We established the fabrication process of the micro-pipette to create a hollow structure using a negative photoresist sheet. The pumping quantity of the micro-pipette was measured while varying the power of the magnets, and the pumping quantity can be controlled by adjusting the distance between the magnets. The maximum pumping quantity was 34.1 nl. Based on the measurement results, we estimated the aspiration force to be 3.41 μN. In order to confirm the calculation results, the aspiration force was measured using a cantilever made from a negative photoresist and determined to be 7.6 μN. Finally, we performed single-cell manipulation using the micro-pipette.