ETD

• cleanroom fabrication
• electromechanical stimulation
• organ-on-chip
• pedot:pss
• soft actuators
• transparency

Faithfully replicating the in vivo cellular microenvironment remains a central challenge in developing functional organ-on-chip (OoC) systems. Electromechanical tissues, such as the myocardium, require the simultaneous stimulation of mechanical and electrical signals for proper cellular maturation and functionality. However, a significant technological gap persists regarding the integration of soft, scalable, and optically compatible actuators within OoC devices: conventional electroactive materials, including ionic polymer–metal composites (IPMCs), are typically opaque and rigid, thereby severely limiting optical access and mechanical compatibility with soft biological tissues.This thesis proposes a fully-polymeric, optically-transparent ionic actuator, termed IPPC (ionic polymer–polymer composite), designed specifically for OoC platforms. Inspired by IPMCs, this device replaces traditional noble metal electrodes with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) coatings deposited onto a Nafion ionic membrane, leveraging the mixed ionic and electronic conductivity of PEDOT:PSS to achieve electrical actuation without the use of metals. Cleanroom fabrication protocols were developed and optimized across four successive experimental cycles. The key parameters investigated include plasma treatment power, annealing temperature, and the number of PEDOT:PSS layers. Deposition techniques—specifically spin coating and doctor blading, the latter applied using custom 3D-printed vacuum chucks—were systematically compared. The fabricated samples were thoroughly characterized electrically via a four-point probe, morphologically through scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), mechanically using dynamic mechanical analysis (DMA) with data processing in MATLAB, and optically via transmittance spectroscopy. Furthermore, sample long-term stability in phosphate-buffered saline (PBS) was rigorously assessed both electrically and mechanically.The optimized and final iteration of the IPPC device, featuring four layers of PEDOT:PSS per side, was subsequently integrated with a localized metallic thin film deposited via electron beam evaporation to serve as robust electrical contact pads. Actuation behavior was evaluated using a custom-built, PCB-driven experimental setup designed to control the input voltage and record the resulting mechanical response. Finally, cell seeding was performed directly on the device to verify its biocompatibility and suitability for high-resolution fluorescence microscopy. The experimental results demonstrate that the newly developed IPPC platform successfully overcomes the historical trade-offs associated with metal-based smart materials. The optimized IPPC exhibits a sheet resistance of approximately 137 Ohm/square. While this represents an expected increase compared to the 3 Ohm/square typical of traditional metallic IPMCs, the fully-polymeric composite compensates by achieving an optical transparency exceeding 60% across the visible spectrum. Mechanically, the IPPC features a compliance modulus of just 169 MPa, marking a prominent 77.5% reduction in elastic modulus compared to the 750 MPa of standard IPMCs, which drastically minimizes mechanical mismatch with soft tissues. Furthermore, the IPPC demonstrated remarkable stability when submerged in PBS; conversely, traditional metallic IPMCs are notorious for undergoing rapid delamination and drastic conductivity loss in physiological environments. Ultimately, by replacing metal electrodes with PEDOT:PSS, this platform reduces bending stiffness, enhances optical transparency, and minimizes electrode footprint, thereby enabling seamless fluorescence imaging of cultured cells. This IPPC platform opens new avenues for studying mechanobiology and electromechanical coupling, contributing to microphysiological models that more accurately mirror in vivo physiology.