Achieving High-Resolution Electrohydrodynamic Printing of Nanowires on Elastomeric Substrates through Surface Modification

Abstract

Stretchable electronics based on nanomaterials has received much interest recently. However, it is challenging to print 1D nanomaterials (e.g., nanowires) with high resolution on stretchable elastomeric substrates. Electrohydrodynamic (EHD) printing has been used to print 1D nanomaterials such as silver nanowires (AgNWs) on stretchable substrates, but the resolution and electric conductivity of the printed patterns are typically low because of the poor wettability of the ink on the surface of the substrates. This paper reports a systematic study of two surface modification methods, UV–ozone treatment and dopamine coating, to modify the surface of polydimethylsiloxane (PDMS), which enables reliable and tunable EHD printing of AgNWs. The dynamic contact angle and the contact angle hysteresis were systematically studied to understand and evaluate the two surface modification methods. This work further investigates the hydrophobic stability of the two surface modification methods that is of critical relevance to the EHD printing, as it determines the shelf life of the treated samples. The effects of treatment dose and aging on the EHD printing performances, such as resolution and conductivity, were studied to find the feasible ranges of the parameters for the surface treatment and printing process. The surface modification methods along with the proper printing conditions can be selected to tailor and optimize the printing performance. A wearable electronic patch with a fractal pattern of AgNWs is printed on the modified PDMS substrate to demonstrate the potential of the reported surface modification for reliable EHD printing of AgNWs for stretchable devices.

Printed Strain Sensors for On‐Skin Electronics

“…[75,125] Nanomaterials, such as AgNWs and CNTs, and conductive polymers, such as PEDOT:PSS and polycaprolactone/poly(acrylic acid) (PCL/PAA), are commonly used to develop the ink. [127] For instance, proper surface modifications allow for printing of the AgNW based ink on a PDMS substrate with high-resolution and complex patterns. [127,128] The PDMS substrate initially exhibited poor wettability with the ink.…”

Recent Advances in High-Throughput Nanomaterial Manufacturing for Hybrid Flexible Bioelectronics

“…In contrast, a CIJ printer charges ink droplets and continually passes them through an electric field formed between two deflection plates, allowing one to control the ink depositions [ 25 ]. Both inkjet printing processes are illustrated in Figure 5 a. DOD printing is highly attractive because it allows for excellent control over deposition thickness, high resolution down to 40 µm, very inexpensive prototyping, and minimal startup costs, but it is also limited by clogging in the minuscule nozzle head, the uneven flow of material to the edge of the print in a process termed the coffee ring effect, and lower throughputs than the previously described methods [ 11 , 22 , 68 ].…”

“…Inkjet printing is another attractive printing method, but it is limited by the requirement that particles are small and well dispersed enough not to clog the inkjet nozzle, and traditional inkjet printing is also too low throughput for industrial scales [ 17 , 21 ]. However, roll-to-roll inkjet printing has been demonstrated, making it a potential target for high-speed device manufacturing [ 22 ]. Electrohydrodynamic printing is an exciting new method that can overcome several of the key challenges in inkjet printing by pulling ionized inks directly to the substrate, but it is likewise limited by constrictive stand-off height requirements and low manufacturing yields [ 21 ].…”

Femtosecond Laser Patterning Wettability‐Assisted PDMS for Fabrication of Flexible Silver Nanowires Electrodes

“…ture will significantly promote the device performance for excellent electrical con duction or isolation. [12,13] The recently reported methods for patterning AgNWs include photolitho graphy, [14,15] laser ablation, [16][17][18] inkjet prin ting, [19][20][21][22][23] printing, [24][25][26][27] mask assis ting, [28][29][30] stamping transfer, [31,32] micro channel selfassembly, [33,34] and substrate surface treatment. [35][36][37] The minimum patterning widths of these methods for AgNWs electrode are summarized in Table S1, Supporting Information.…”

“…Laser abla tion [18] is likely to damage heatsensitive plastic substrates or fuse AgNWs, because of the high temperature generated during laser processing. Inkjet printing [19][20][21][22][23] is a facile onestep, maskfree patterning techniques, but its min imum patterning accuracy will be limited by the nozzle size. To avoid nozzles clog, nozzle diameter, printing parameters, the formulation of ink during printing AgNWs are need to be adjusted appropriately to match each other.…”