Tailoring inkjet-printed PEDOT:PSS composition toward green, wearable device fabrication

Abstract

Inkjet printing remains one of the most cost-efficient techniques for device prototyping and manufacturing, offering considerable freedom of digital design, non-contact, and additive fabrication. When developing novel wearable devices, a balanced approach is required between functional, user-safe materials and scalable manufacturing processes. Here, we propose a tailor-made ink formulation, based on non-hazardous materials, to develop green electronic devices aimed at interfacing with humans. We demonstrate that developed ink exhibits high-resolution inkjet printability, in line with theoretical prediction, on multiple wearable substrates. The ink's chemical composition ensures the pattern's enhanced electrical properties, mechanical flexibility, and stability in water. The cytocompatibility evaluations show no noxious effects from printed films in contact with human mesenchymal stem cells. Finally, we fabricated a printed wearable touch sensor on a non-woven fabric substrate, capable of tracking human steps. This is a step toward the development of green wearable electronics manufacturing, demonstrating a viable combination of materials and processes for biocompatible devices.

Boosting the Performance of PEDOT:PSS Based Electronics Via Ionic Liquids

“…In addition, there is a general trade-off between conductivity and stretchability in PEDOT:PSS as enhancing conductivity of PEDOT:PSS often involves creating a more densely packed and interconnected structure, which can limit its ability to be stretched without fracturing. [25] Therefore, researchers are actively working on addressing these challenges and exploring ways to improve the performance of PEDOT:PSS in bioelectronic applications by pre-treatment or post-treatment with additives such as polar solvents, [26] strong acids, [27] surfactants, [28] crosslinkers, [29] and so on (Table 1). When added to PEDOT:PSS suspension, polar solvents, including ethylene glycol (EG), glycerol, dimethyl sulfoxide (DMSO), and polyethylene glycol (PEG), can reduce the coulombic attraction between PEDOT and PSS segments through high-polarity group screening.…”

“…Therefore, researchers are actively working on addressing these challenges and exploring ways to improve the performance of PEDOT:PSS in bioelectronic applications by pre‐treatment or post‐treatment with additives such as polar solvents, [ 26 ] strong acids, [ 27 ] surfactants, [ 28 ] crosslinkers, [ 29 ] and so on ( Table 1 ). When added to PEDOT:PSS suspension, polar solvents, including ethylene glycol (EG), glycerol, dimethyl sulfoxide (DMSO), and polyethylene glycol (PEG), can reduce the coulombic attraction between PEDOT and PSS segments through high‐polarity group screening.…”

Inkjet printing P(VDF-TrFE-CTFE) actuators for large bending strains

“…A number of advances have been reported in IJP to fabricate parts of EAP sensors and actuators, while only few have printed the entire transducer. Poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) has been printed on PVDF [16,17] and interpenetrating polymer network [18] membranes to produce ionic EAP actuators; on PVDF to make piezoelectric bimorph actuator components [19]; and on P(VDF-TrFE) to make piezoelectric sensors [20]. Inks and processes for IJP EAP have been developed for P(VDF-TrFE) in [21], and for both P(VDF-TrFE) and P(VDF-TrFE-CTFE) in [22], whereas the latter study further used sputtering to deposit Au electrodes to produce force sensors.…”

Recent progress in thermal management for flexible/wearable devices

“…The design and development of advanced wearable devices still pose challenges because of the need to integrate electronic, electrochemical, electro-optical, or multiple types of functionality on a platform that is soft, compact, lightweight, flexible, and stretchable [12,13] . To do so, various manufacturing technologies, such as laser processing [14][15][16][17] , transfer printing [18][19][20][21] , and inkjet printing [22][23][24][25][26] , have been used to fabricate a flexible/stretchable device platform. Ensuring long-term reliability and biocompatibility during human body motion, especially in outdoor activities involving external heat exposure and metabolic heat generation, adds to the challenges in material/structure development and device design.…”