USPA's application to cell puncture

This article presents an untethered stick-slip piezoelectric actuator (USPA) with decimeter stroke and nanometer resolution. Here, four bar-shaped piezo-legs are bonded onto an alumina plate to form a simple configuration, and the actuator’s two-DOF movement is driven with an onboard circuit that converts the battery’s DC signal into multi-channels of sawtooth voltages. Interestingly, the stick-slip movements somewhat imitate the Siberian roe deer’s special gait in terms of the switching function between the stable- and unstable-contact states. First, by using the lumped-parameter model with triple mechanical branches, the piezo-leg’s resonant frequencies of the 1st, 2nd, and 3rd bending modes were structurally modulated to generate the stick-slip movement. Then, a prototype with the size of 80 × 60 × 80 mm3 was fabricated to assess its vibrating, moving, and carrying performance. At 2065 Hz frequency, the USPA yielded the maximal speed and the maximal payload of 1257.9 μm/s and 630 g, respectively. Installed with a lithium battery with 3.7 V voltage and 200 mAh capacity, the maximal running distance reached 6.92 dm, while the minimal step displacement was 12.2 nm. As a practical tool, the USPA is potentially applicable to the robotic-assistant precise operation, e.g., cell puncture and detection of wafer deficiency.