The development of microsystems is a rapidly evolving field which enables a wide range of applications for electroactive materials. Microelectromechanical actuators based on electronically conducting polymers are elaborated with an up‐scalable process. Commercial poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is chosen as an easily processable electrode to ensure the reproducibility for further technological production and practical applications. First, the improvement of electrical, electrochemical, and mechanical properties of the PEDOT:PSS electrodes is described by incorporating reactive additives, that is, glycol‐based monomers (mPEG) as polyethylene oxide (PEO) network precursors. Moreover, the custom fit layer‐by‐layer (LbL) process to integrate these PEDOT:PSS/PEO composite electrodes into trilayer microactuators is presented. The incorporation of PEO within PEDOT:PSS improves significantly the electromechanical performances of the resulting microactuators with significant strain (0.82%) and high output forces (472 µN) compared to similar PEDOT based or pristine PEDOT:PSS microactuators. This work provides also the first demonstration that mechanical strain sensing behavior, extensively studied at macroscale, still occurs at microscale for these trilayer systems. Additionally, to this proof of concept, it highlights that output signal is significantly enhanced by downsizing the devices compared to similar macroscale samples. These results open promising perspectives in the development of numerous applications for soft and scalable microactuators and microsensors.

Mass production of conducting polymer actuators with reliable performance is envisaged in the field of artificial muscles. In this study, inkjet printing and spin coating-two established technologies for large-scale production-were combined for microactuator fabrication. Actuators based on poly(3,4ethylenedioxy-thiophene):poly(styrene sulfonate) electrodes (PEDOT:PSS, 2.2 m thick, 190 S cm −1), which were inkjet-printed onto a spin-coated membrane of an interpenetrating polymer network (IPN) thin film composed of nitrile butadiene rubber and poly(ethylene oxide) (PEDOT:PSS-IPN-PEDOT:PSS) with a total thickness of 12.7 m, were prepared and studied. Our goal was to investigate the performance of the trilayers in linear actuation, in aqueous and organic (propylene carbonate) solutions of bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) used as electrolytes, and in bending actuation in air using an ionic liquid as the electrolyte. Electro-chemo-mechanical deformation (ECMD) measurements were consistent with electrochemical measurements showing a strain of 3% in aqueous electrolyte and 1% in propylene carbonate. A strain of 0.14% in the bending mode in the ionic liquid was observed due to electric double layer charging, while in electrolyte solutions, redox reactions determined the linear actuation properties. In the aqueous electrolyte, a specific capacitance of 193 F g −1 was measured for the printed PEDOT:PSS films, with potential for applications in supercapacitors.

Electronic conducting polymer based-actuators have attracted lots of interest as alternative materials to traditional piezoelectric and electrostatic actuators. Their specific characteristics such as their low operating voltages and large strains should allow them to adapt better to soft microstructures. Recently, poly (3,4-ethylenedioxythiophene) (PEDOT) e based ionic actuators have overcome some initial stumbling blocks to widespread applications in the microfabricated devices field. These trilayer bending microactuators were fabricated (i) by sequential stacking, using a layer by layer polymerization (LbL) of conducting polymer electrodes and a solid polymer electrolyte and (ii) by micro-patterning, using standard microsystems processes. While microfabrication processing of a trilayer actuator, involving no manual handling has been demonstrated, their bending performances remain limited for practical applications. Moreover, the complete characterization of their electrical, electrochemical, and mechanical properties has never been investigated. This paper describes the optimization of PEDOT electroactive electrodes synthesized with a vapor phase polymerization process. Influence of synthesis parameters on thickness, electronic conductivity and volumetric charge density were studied to determine the guidelines for synthesizing highly efficient electrodes. Afterwards, these parameters are used to guide the LbL synthesis process of ultrathin trilayer actuators. Electrochemical and mechanical properties of the resulting microactuators have been thoroughly characterized. Bending deformation and output force generation have been measured and reached 0.5% and 11 mN respectively. This constitutes the first characterization of ionic PEDOT-based microactuators operating in air of such a thin thickness (11 mm dry and 18.3 mm swelled in 1-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMImTFSI)). These actuators and their actuation properties are promising for future soft microsystem devices where the use of polymer actuators should be essential.

Actuation and sensing with electroactive polymers should be a chance for flexible MEMS but their micromachining and integration are still not mature. Some innovative materials and microfabrication processes are still expected. In this paper, a first full elaboration of polymeric microtransducers (MTs) including integration and operation has been described. The fabrication process relies on commercially available poly(3,4-ethyledioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) conductive ink, onto flexible SU-8 photoresist microchip. Batch-fabrication of complex flexible monolithic units comprising individually addressable MTs of different shapes, is demonstrated. The resulting polymeric MTs show both very promising bending actuation and strain sensing properties in open-air. Remarkably, the microfabrication process did not impact the performances compared to material fabricated with laser cutting. This work paves the way for flexible MEMS development for soft microrobotics, microfluidics in medical and spatial applications.

Soft ionic actuators and sensors have been intensively studied over the last 20 years. The bending trilayer configuration has been considered a standard architecture, allowing the development of new materials and their optimization. However, bending deformation remains low in force output and presents limited integration capabilities in fast emerging fields like humanoid robotics and actuating textiles. A generalizable architecture of asymmetric supercapacitor‐like trilayers is presented to develop open‐air linear artificial muscles that actuate and sense. First, tuning of electromechanical properties of asymmetric electrodes is performed separately by combining poly(3,4‐ethyl‐enedioxythiophene):poly(styrene sulfonate) with a polyethylene oxide network and 1‐ethyl‐3methylimidazolium bis(trifluoromethanesulfonyl)imide as additives. By varying their content, electronic conductivity can be tuned between 20 and 457 S cm−1, Young's modulus from 1.5 to 0.27 GPa, and volumetric charge density increased by 36%. Asymmetric trilayers are then fabricated using a simple layer stacking process by selecting the optimal combination of materials according to an electromechanical model. Linear strain of 0.5% is obtained in 30 s under ±2 V with 70% of the deformation within 5 s and blocking stress as high as 0.3 MPa. When mechanically stimulated, these asymmetric trilayers demonstrate linear sensing as well, with a sensitivity of 0.38 mV %−1.