Bonafè Filippo, Decataldo Francesco, Cramer Tobias, Fraboni Beatrice
Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Bologna, 40127, Italy.
Adv Sci (Weinh). 2024 May;11(18):e2308746. doi: 10.1002/advs.202308746. Epub 2024 Mar 1.
The conversion of electrochemical processes into mechanical deformation in organic mixed ionic-electronic conductors (OMIECs) enables artificial muscle-like actuators but is also critical for degradation processes affecting OMIEC-based devices. To provide a microscopic understanding of electroactuation, the modulated electrochemical atomic force microscopy (mEC-AFM) is introduced here as a novel in-operando characterization method for electroactive materials. The technique enables multidimensional spectroscopic investigations of local electroactuation and charge uptake giving access to the electroactuation transfer function. For poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) based microelectrodes, the spectroscopic measurements are combined with multichannel mEC-AFM imaging, providing maps of local electroactuation amplitude and phase as well as surface morphology. The results demonstrate that the amplitude and timescales of electroactuation are governed by the drift motion of hydrated ions. Accordingly, slower water diffusion processes are not limiting, and the results illustrate how OMIEC microactuators can operate at sub-millisecond timescales.
在有机混合离子 - 电子导体（OMIECs）中，将电化学过程转化为机械变形不仅能够实现类人工肌肉致动器，对于影响基于OMIEC的器件的降解过程也至关重要。为了从微观层面理解电驱动，本文引入调制电化学原子力显微镜（mEC - AFM）作为一种用于电活性材料的新型原位表征方法。该技术能够对局部电驱动和电荷吸收进行多维光谱研究，从而获得电驱动传递函数。对于基于聚（3,4 - 乙撑二氧噻吩）聚苯乙烯磺酸盐（PEDOT:PSS）的微电极，光谱测量与多通道mEC - AFM成像相结合，可提供局部电驱动幅度和相位以及表面形态的图谱。结果表明，电驱动的幅度和时间尺度受水合离子的漂移运动控制。因此，较慢的水扩散过程并非限制因素，研究结果还说明了OMIEC微致动器如何能够在亚毫秒时间尺度上运行。
