Programmable electric tweezers

The interaction between a single microscopic object such as a cell or a molecule and electromagnetic field is fundamental in single-object manipulation such as optical trap and magnetic trap. Function-on-demand, single-object manipulation requires local high-freedom control of electromagnetic field, which remains challenging. Here, we propose a manipulation concept: programmable single-object manipulation, based on programming the electromagnetic field in a multibit electrode system realized on a programmable electric tweezer (PET) with four individually addressed electrodes. Its probe-integrated electrode array supports spatial-selective manipulation, while the adjustable electrode gaps enable manipulating multiscale targets. The independent programming of the electrical signals of each electrode further allows using multiple electric principles to achieve multiscale and spatiotemporal programmable control and in situ measurements, marking a transition from function-fixed single-object manipulation to function-on-demand single-object manipulation. Last, with integrated functions of PET, we demonstrate multistep manipulation to measure the spontaneous relaxation of DNA supercoiling, highlighting the versatility of PET in uncovering stochastic biophysical phenomena at the single-molecule level.