Highly transparent and flexible circuits through patterning silver nanowires into microfluidic channels

Abstract

The development of flexible and transparent devices requires completely transparent and flexible circuits (TFCs). To overcome the disadvantages of the previously reported TFCs that are partially transparent, lacking pattern control, or labor consuming, we achieve true TFCs via a facile process with precise pattern control, exhibiting concurrent high transparency, conductivity, flexibility, stretchability, and robustness. A highly transparent and flexible conductive film is first made through spin coating silver nanowires (AgNWs) onto polydimethylsiloxane (PDMS), and demonstrates simultaneous high transparency (90.86%) and low sheet resistance (3.22 Ω sq-1). Taking advantage of microfluidic technology, circuits with ultraprecise and complex patterns from the microscale to milliscale are obtained through spin coating of AgNWs into microfluidic channels on PDMS. Without elaborate processing, this method may be suitable for mass production, which would contribute enormously to potential applications in wearable medical equipment and transparent electronic devices.

Flexible Microfluidics: Fundamentals, Recent Developments, and Applications

“…In addition to sensing elements, circuitry and interconnects with excellent bendability and stretchability play an important role to construct a fully wearable device. Figure 10h-j represent some microfluidic-based flexible stretchable circuits and interconnects [176,181]. The use of fluidic interconnects enables extremely large deformation and stress, thereby eliminates the crack issues that usually occur in solid-metal-based components.…”

“…The use of fluidic interconnects enables extremely large deformation and stress, thereby eliminates the crack issues that usually occur in solid-metal-based components. Sun et al [181] reported the fabrication of flexible conductive microfluidic circuits with potential applications in wearable sensors and implantable biomedical devices, Figure 10j. PDMS was first treated using poly(vinyl alcohol)/glycerol (PVA/Gly), followed by the deposition of silver nanowires (AgNWs) on the microfluidic channels.…”

“…(j) Flexible conductive microfluidic circuit. Adapted with permission from Sun et al[181]. (k,l) Artificial placenta-type blood oxygenator based on flexible microfluidics.…”

Fabrication of Two-Dimensional and Three-Dimensional High-Resolution Binder-Free Graphene Circuits Using a Microfluidic Approach for Sensor Applications

“…Different microfluidic approaches were used earlier for the fabrication of electronic circuits or microfluidic devices: 35,[39][40][41][42] water-dispersed multiwall carbon nanotubes (MWNTs), as electrolytes) to the surface, which was then followed by another wax printing to create hydrophobic structures. 42 Similarly, Lee and coworkers developed paper-based microfluidic assay system through wax printing at high temperatures (127-204 ºC).…”

Advances in Liquid Metal-Enabled Flexible and Wearable Sensors

“…Although circuits fabricated by carbon-based materials are highly stretchable, they are not as conductive as those fabricated by metals. Nanoparticles of rigid metals are applied to design soft circuits with high conductivity, among which silver nanoparticles have been extensively studied [47][48][49][50][51][52][53]. Moreover, liquid metal, mainly refers to metal whose melting point is around the room temperature, is increasingly popular in the area of soft circuits because it possesses both good deformability and conductivity [54].…”