A Simple Silver Nanowire Patterning Method Based on Poly(Ethylene Glycol) Photolithography and Its Application for Soft Electronics

Abstract

Hydrogel-based flexible microelectrodes have garnered considerable attention recently for soft bioelectronic applications. We constructed silver nanowire (AgNW) micropatterns on various substrates, via a simple, cost-effective, and eco-friendly method without aggressive etching or lift-off processes. Polyethylene glycol (PEG) photolithography was employed to construct AgNW patterns with various shapes and sizes on the glass substrate. Based on a second hydrogel gelation process, AgNW patterns on glass substrate were directly transferred to the synthetic/natural hydrogel substrates. The resultant AgNW micropatterns on the hydrogel exhibited high conductivity (ca. 8.40 × 103 S cm−1) with low sheet resistance (7.51 ± 1.11 Ω/sq), excellent bending durability (increases in resistance of only ~3 and ~13% after 40 and 160 bending cycles, respectively), and good stability in wet conditions (an increase in resistance of only ~6% after 4 h). Considering both biocompatibility of hydrogel and high conductivity of AgNWs, we anticipate that the AgNW micropatterned hydrogels described here will be particularly valuable as highly efficient and mechanically stable microelectrodes for the development of next-generation bioelectronic devices, especially for implantable biomedical devices.

High-Performance Resistive Pressure Sensor Based on Elastic Composite Hydrogel of Silver Nanowires and Poly(ethylene glycol)

“…The process used to fabricate piezoresistive pressure sensors comprising patterned AgNW-PEG on flexible PET is schematically illustrated in Figure 1 , including step-by-step photographs. A slightly modified version of a PEG photolithography process described in our previous works [ 48 , 49 , 50 ] was employed to construct each active layer of AgNW-PEG. In contrast to our previous studies the objective of the present work was to directly study the influence of AgNWs and PEG hydrogel upon the performance of contact resistive pressure sensors.…”

Soft Material-Enabled, Flexible Hybrid Electronics for Medicine, Healthcare, and Human-Machine Interfaces

“…NWs are often adopted as sensing materials due to unique electrical and mechanical properties. Silver nanowires (AgNWs) patterning and films are demonstrated [ 63 , 73 ]. As shown in Figure 1 j, aligned NWs can be grown on the substrate similar to CNTs.…”

“…This electrode array allowed 8% and 15% elongation in separate directions, and detected approaching objects up to 7 cm away due to absorption of the object’s electric field. Another study developed flexible, biocompatible microelectrodes by patterning AgNWs onto a hydrogel substrate of PEG, agarose, and PAAM, allowing flexibility to bend up to a 10 mm radius [ 73 ]. By patterning thin Au on PI substrates, electrooculography (EOG) electrodes can be developed to withstand over 30% strain and 500 micron bending radius [ 8 ].…”

Coat-and-print patterning of silver nanowires for flexible and transparent electronics

“…However, there are still several limitations to both methods. The mask-based patterning techniques, such as photolithography 40 , stencil screen, 39 wet/dry transfer, 37 and ultraviolet/ozone (UV/O 3 ) irradiation, [41][42][43] are capable of producing highly transparent patterns, as this type of techniques can take advantage of state-of-the-art Ag NWs with high aspect ratio. However, mask use typically requires complex and high-cost processes that yield limited patterning area, as well as low patterning efficiency.…”