Ink Development and Printing of Conducting Polymers for Intrinsically Stretchable Interconnects and Circuits

Abstract

the significant advancements in flexible electronics, there has been a growing interest in realizing wearables on similar substrates. Emerging areas are artificial skin on prosthetics or epidermal, healthmonitoring sensors to bring personalized medicine to the next level. These envisioned electronic devices should ideally be conformable to the skin and/or accommodate for deformations such as twisting and stretching. Therefore, the next frontier is to merge mechanical and electrical requirements and realize not only flexible but also elastic electronics that are compatible with the soft, curvilinear surfaces of biological tissue. [2-11] Recent progress in stretchable, conductive polymers has led to a number of intrinsically stretchable devices and sensors including stretchable transistors, [12-16] logic circuits, [17,18] light emitting devices, [19-21] strain, [21-23] touch, [24] and temperature [25,26] sensors. Despite these first demonstrations of intrinsically stretchable devices, there are still several challenges on the road toward elastic sensors for health monitoring and conformable integrated circuits. Here, we address one essential, but often underestimated circuit element that is paramount for the realization of all elastic circuits, namely reliable, stretchable interconnects that link the constituent circuit components. Furthermore, for elaborated circuits, interconnects have to cross each other and need to be deposited on different layers. Therefore, through connections, so-called via holes are crucial as well. One solution is to render rigid, highly conductive materials stretchable, for example by advanced structural engineering approaches using wavy patterns [27-30] or 3D kirigami structures. [31] These approaches, however, are not readily scalable, since processes such as vacuum evaporation or photolithography are required and the resulting patterns occupy large areas. An alternate approach toward elastic interconnects, is the development of intrinsically stretchable, electrically conductive materials. Previously investigated thin-films of the conductive polymer mixture (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) (PEDOT:PSS), which was doped with various ionic liquids, were found to be promising in terms of their electrical conductivity and stretchability. [32] To enable patterning of such elastic conductors and therewith their application in stretchable interconnects and to facilitate Printable elastic conductors open up new opportunities in large-area fabrication of wearable electronics and prosthetics. Furthermore, they have the potential to advance health monitoring and continuous diagnostics by implementing sensor arrays in close proximity to the skin. Such devices need to be comfortable to wear and must accommodate strains and deformations such as twisting and stretching. A conductive polymer ink for elastic interconnects and electrodes is introduced. The processability by inkjet printing enables versatile, contactless, and maskless large area processing. The printed PEDOT:PSS-bas...

Device Based on Polymer Schottky Junctions and Their Applications: A Review

“…We prepared a PPy hydrogel by using a multiphase reaction (organic phase and water phase), which was able to be casted over a large area for a uniform film [55]. This approach is highly tunable and versatile as it offers great convenience in controlling the dopant molecules and doping level that affect the morphology and properties of polymers [51], [56]. Moreover, such a solution-based synthetic method can introduce new functions to polymers [57].…”

“…For example, treating PEDOT:PSS using mild acids instead of strong acids increases the mechanical flexibility and stability for organic solar cell applications [62]. Introducing plasticizing additives such as Zonylfluorosurfactants or ionic liquids to PEDOT:PSS can render this material mechanically stretchable to enable the applications in stretchable circuits, bioelectronics, and flexible electronics [56], [63], [64]. It is explained that the additives that also function as dopants weaken the interactions between PEDOT and PSS domains and lead to charge delocalization and transport and increased crystallinity/molecular order [65], [66].…”

“…Since polymers are pure conductivity material, the introduction of conductive materials will construct a hybrid framework and improve the conductivity of the polymeric system [67]. By adding dodecyl benzene sodium sulfonate (DBSS), it was reported that a kind of PEDOT:PSS enhances its conductivity as high as 700 S cm -1 and tolerates strain over 100% [56].…”

Inkjet Printing Controllable Polydopamine Nanoparticle Line Array for Transparent and Flexible Touch‐Sensing Application

“…[1][2][3][4][5][6][7][8] Among these fabrication techniques, drop-on-demand inkjet printing using functional material inks has received considerable attention. Inkjet printing presents a promising approach toward the realization of cost-effective, environmental-friendly, and scalable printed electronics, [9,10] and thus holds significant potential for flexible, [11,12] stretchable, [13,14] and hybrid [15,16] electronics applications. However, a major limitation of inkjet printing is low resolution (typical feature size ranges from 35 to 100 μm), [17,18] which hinders further development of this technique for advanced microelectronics applications.…”

Rapid Custom Prototyping of Soft Poroelastic Biosensor for Simultaneous Epicardial Recording and Imaging

“…Advanced strategies involve the use of conducting viscoelastic polymers or silicone composites containing conductive nanofillers to serve as dispensable inks for a nozzle injection system that allows for automated rapid prototyping. [8][9][10][11] To this end, it requires precise control of the rheological properties of the inks in order to (1) ensure high-precision printability for sophisticated rendering at the microscale and (2) prevent the hindering of the densely dispersed nanofillers from the polymerization of the inks. 12 Despite great successes, these materials exhibit mechanical and electrical hysteresis under periodic large strain cycles due to their viscoelastic nature or/and result in irreversible degradation in conductivity due to the difficulty of maintaining the percolation network of the conductive nanofillers.…”