A novel piezoelectric inchworm actuator driven by one channel DC signal is developed in this paper to simplify excitation signal of the inchworm actuators, and the clamping force of the developed actuator is generated by a DC motor and two permanent magnets. The piezoelectric stack is excited by a sensing signal, which is generated by the separate photoelectric sensor to detect the position of the rotational permanent magnets. A mathematical model is established to predict the motion of the slider. The prototype of the proposed piezoelectric actuator is fabricated, and mechanical output performance is measured. At a voltage of 75 V and frequency of 3.2 Hz, the average output step is 0.241 μm under no-load conditions. The proposed inchworm actuator can be operated by just one channel DC signal and the output displacement is stable, which provides a new idea for the integration design of the piezoelectric actuators in the future.

A low frequency structure-control-type inertial actuator using miniaturized bimorph piezoelectric vibrators has been proposed to achieve high resolution and high stability with a large linear stroke. These vibrators are fabricated by bonding, thinning and patterning fabrication processes, which are beneficial to realize miniaturization and increase output performance for the system. A theoretical model based on work-energy analysis is established to predict the output displacement characteristics. An experimental system is built to evaluate the performance of the proposed actuator. Experimental results indicate that the stable minimum step displacement is 0.03 μm under a square wave signal of 5 V, 50 Hz and a clamping difference of 3.5 mm. Under the condition of 7 V and 50 Hz, the sample standard deviation is 0.0337 μm in repeatability test. The proposed actuator achieves a stable and accurate linear bidirectional motion with high resolution, high stability, low power consumption and a large working stroke.

In order to decrease the backward motion and improve the motion efficiency, a walking type piezoelectric actuator has been proposed with two ‘legs’ based on the parasitic motion of obliquely assembled PZT stacks. The structure and motion principle of the proposed walking type piezoelectric actuator are described, and its experiment system is set up. Experimental results indicate the proposed piezoelectric actuator could reduce the backward motion effectively. The minimum backward rate α = 2.26% is achieved under the condition of the phase difference θ = 180°, the input voltage U = 120 V and the input frequency f = 1 Hz; the minimum stepping displacement is 0.24 μ m under the condition of U = 5 V, f = 1 Hz and θ = 180°; the maximum speed V _max is 2472 μ m s ⁻¹ under the condition of U = 120 V and θ = 180°; the maximum vertical load force F _Vmax = 6850 g under the condition of U = 120 V, f = 1 Hz and θ = 180°. Furthermore, a dynamic model of the whole walking type piezoelectric actuator is established, and it has been employed to simulate the motion of the proposed walking type piezoelectric actuator. Simulation results present a great agreement of experimental results. This study shows a novel idea for the design of piezoelectric actuators to eliminate the influence of backward motion and improve the output efficiency of the actuator.

The piezoelectric inchworm actuator with high-positioning accuracy and large output force is a potential device to implant microelectrode in the invasive brain–computer interface (BCI). However, the traditional piezoelectric inchworm actuator adopts multichannel electrical control signals from external equipment and rigid-to-rigid friction contact to drive, resulting in complex control and uneven friction. To solve the above problems, in this article, magnetorheological elastomer (MRE) is first proposed as the clamping material of the piezoelectric inchworm actuator. An MRE–capillary–cover sandwich structure is adopted to achieve rigid-to-elastomeric clamping. The driving and clamping actions of the actuator are controlled by two cam mechanisms mounted on the same shaft, and a battery can feed the actuator. A kinetic model is established to analyze and predict the actuator motion. Several crucial clamping parameters are explored, and the performance experiments are conducted to evaluate actuator characteristics. A verification experiment is carried out to prove the feasibility of the microelectrode implantation in the pig brain (0.6% agarose gel). The actuator can reach the maximum velocity of 1250.4 μ m/s and the maximum output force of 420 mN; in the forward/backward motion, the minimum step is 0.5837/0.5912 μ m, and the repeatability is 0.0465/0.0469 μ m; thus, the actuator has great application potential in BCI.

A piezoelectric vibration energy harvester with a broad bandwidth (>15 Hz) is proposed based on a flexible self-buckled bridge. The polymer sheet, thin metal foil, and thinned piezoelectric ceramic film are bonded to constitute the flexible buckled bridge with the total thickness of 200 μm. Its good flexibility is benefit to obtain low resonant frequency (<200 Hz). A “T” shaped proof mass is used to provide a concentrated force at the center of the bridge for buckling easily and decrease the resonant frequency. The natural buckled arc after the bonding process results in a nonlinear phenomenon at the excited acceleration of 0.25 g. The harvester is capable of achieving a maximum peak open-circuit voltage of 15.18 V and maintaining a bandwidth of 15 Hz (90–105 Hz) at an applied acceleration amplitude of 2.0 g. Meanwhile, the harvester generates the maximum effective power of 0.6 mW and the maximum effective power density of 6.9 mW/cm³ at 2.0 g and 105.3 Hz. The normalized power density reaches 0.36 mW cm⁻³ g⁻² Hz⁻¹. The harvester with larger proof mass results in low resonant frequency and a broader bandwidth of 30 Hz (67–97 Hz). Moreover, the harvester performs good reliability at an acceleration amplitude of 2.0 g.