Conducting polymer actuators have shown wide application prospects in the field of biomedical sensors and micro-/nanorobotics. In order to explore more applications in biomedical sensing and robotics, it is essential to understand the actuator static behavior from an engineering perspective, before incorporating them into a design. In this article, we have established the mathematical model of a trilayer polypyrrole (PPy) cantilever actuator and validated it experimentally. The model helps in enhancing the efficiency and in improving the performance, predictability, and control of the actuator. The thermal expansion analogy, which is similar to volume change of the multilayer PPy actuator due to ion migration, has been considered to develop a mathematical model in COMSOL Multiphysics. To further validate the actuator deformation predicted by the mathematical modeling, a multilayer PPy actuator was fabricated by electrochemical synthesis and the experimentally determined deflection of the actuator was compared to simulation data. Both the theoretical and experimental results depict that the model is effective for predicting the bending behavior of multilayer PPy actuators at different input voltages.

The performance of supercapacitors is directly influenced by the conductivity of polypyrrole, which serves as the electrode material. In order to balance considerations of cost-effectiveness and conductivity, this study employs magnetron sputtering to fabricate a copper–tin alloy layer as the conductive layer for polypyrrole. The deposition of a copper–tin alloy film through magnetron sputtering has a significant impact on the polymerization effect of pyrrole as well as being a crucial factor influencing the performance of supercapacitors. Various parameters, including working pressure, sputtering time, and sputtering power, affect the conductivity of the copper–tin alloy film. Furthermore, the degree of influence of each parameter on the conductivity of the copper–tin alloy film varies. This study utilizes an orthogonal experimental design to investigate the impact of various factors and levels on the conductivity and uniformity of a metal film. The objective is to optimize the process parameters for the creation of a copper–tin alloy film with desirable characteristics. Experimental results indicate that the working voltage, sputtering time, and sputtering power significantly influence the coefficient of variation, deposition rate, target current, and operating voltage of the film. Furthermore, FT-IR, XRD, and SEM tests are conducted on samples prepared using the identified optimal process parameters. In addition, we demonstrate various approaches to enhance the experiment’s reliability. The findings indicate that the most favorable process parameters for achieving optimal results are a working pressure of 0.065 Pa, a sputtering time of 20 min, and a sputtering power of 70 W. It was observed that the sputtering time significantly influences the uniformity of the copper–tin alloy film, whereas the sputtering power has a minimal impact on its uniformity. The deposition rate is primarily influenced by the working pressure, with the greatest effect observed. Conversely, the sputtering time has the least impact on the deposition rate. Similarly, the target current is predominantly affected by the sputtering power, exhibiting the greatest influence, while the sputtering time has the least effect. Furthermore, the working voltage is most significantly influenced by the working pressure, whereas the sputtering time has the least impact on the working voltage.

Aerosol jet printing technology was utilized to enhance the quality of the four printing processes, with the objective of producing high-quality silver wires. Silver nanowires were used as the ink media. Subsequently, micro-flexible strain sensors were fabricated on PI substrates. A comprehensive investigation was conducted to ascertain the impact of systematic variation in four pivotal printing process parameters-sheath gas flow rate (30–50 sccm), nozzle height (8–13 mm), atomization current (0.25–0.50 mA), and printing speed (1–3.5 mm s⁻¹) on the width of printed lines, their morphology, and the resistance exhibited. The objective of this investigation was to achieve the printing of silver lines with reduced line widths and diminished resistances. Concurrently, the influence degree of these four process parameters was analyzed. Subsequent to the optimization of the parameters, the fabrication of flexible strain sensors was successfully executed, and their performance was duly validated. The test results show that the line quality of the silver wire is good and the resistance is low in the range of 40–45 sccm of sheath gas flow, 10–12 mm of working distance, 0.35–0.45 mA of atomization current, and 2–2.5 mm s⁻¹ of printing speed. Finally, the strain sensor with a line width of 40 μm was printed on the PI substrate under the conditions of sheath gas flow rate of 40 sccm, working distance of 11 mm, atomization current of 0.4 mA, and printing speed of 2 mm s⁻¹. The flexible strain sensor prepared under these conditions exhibited a sensitivity of 65.7 and a hysteresis rate of 4.37% at 0%–5% strain, adhesion rating to substrate reaches 4B level, demonstrating good repeatability.

In this paper, a 3D printing system for a thermal battery electrode ink film is set up and investigated based on the on-demand microdroplet ejection technology. The optimal structural dimensions of the spray chamber and metal membrane of the micronozzle are determined via simulation analysis. The workflow and functional requirements of the printing system are set up. The printing system includes a pretreatment system, piezoelectric micronozzle, motion control system, piezoelectric drive system, sealing system, and liquid conveying system. Different printing parameters are compared to obtain optimized printing parameters, which can be attributed to the optimal pattern of the film. The feasibility and controllability of 3D printing methods are verified by printing tests. The size and output speed of the droplets can be controlled by adjusting the amplitude and frequency of the driving waveform acting on the piezoelectric actuator. So, the required shape and thickness of the film can be achieved. An ink film in terms of nozzle diameter = 0.6 mm, printing height = 8 mm, wiring width = 1 mm, input voltage = 3 V and square wave signal frequency = 35 Hz can be achieved. The electrochemical performance of thin-film electrodes is crucial in thermal batteries. The voltage of the thermal battery reaches its peak and tends to flatten out at around 100 s when using this printed film. The electrical performance of the thermal batteries using the printed thin films is found to be stable. This stabilized voltage makes it applicable to thermal batteries.

Micro-cantilever has shown wide application prospect in the field of micro-sensors, actuators, gyroscope, and so on. There are abundant research studies on simple cantilever beam models, but there are few on S-shaped folding cantilever with complex structure, although it is widely used. In order to study the deformation failure of S-shaped folding cantilever, the force analysis of S-shaped folding cantilever was carried out in this article, and the stress values of different positions under the external load of the cantilever were deduced. The finite element model about S-shaped folding cantilever was built based on software ANSYS. The theoretical calculation was compared with the finite element calculation, and the results showed that the max stress is 681 MPa based on the derived theoretical formula, the max stress is 673 MPa based on the ANSYS, the error is 1.18%, which can prove formula is accurate. To further validate the stress predicted by the mathematical modeling, a micro-force testing platform was built to test the cantilever. Since the stress value cannot be measured directly in the test, the force corresponding to the stress was taken as standard and compared it with the simulation. The tested external force was corresponding the yield limit. The results showed that the experimental force was 0.06462 N before the plastic deformation occurred, the theoretical outcome was 0.065231 N corresponding the yield limit, the error was 0.94%. Both simulation and experimental results depict that the theoretical model is effective for predicting the stress of the S-shaped folded cantilever. The theoretical model helps to enhance the efficiency, and improve the performance, predictability, and control of the S-shaped folding cantilever.