Fabrication of Stretchable Circuits on Polydimethylsiloxane (PDMS) Pre-Stretched Substrates by Inkjet Printing Silver Nanoparticles (original) (raw)
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Screen-Printing Fabrication and Characterization of Stretchable Electronics
Scientific Reports, 2016
This article focuses on the fabrication and characterization of stretchable interconnects for wearable electronics applications. Interconnects were screen-printed with a stretchable silver-polymer composite ink on 50-μm thick thermoplastic polyurethane. The initial sheet resistances of the manufactured interconnects were an average of 36.2 mΩ/◽, and half the manufactured samples withstood single strains of up to 74%. The strain proportionality of resistance is discussed, and a regression model is introduced. Cycling strain increased resistance. However, the resistances here were almost fully reversible, and this recovery was time-dependent. Normalized resistances to 10%, 15%, and 20% cyclic strains stabilized at 1.3, 1.4, and 1.7. We also tested the validity of our model for radio-frequency applications through characterization of a stretchable radio-frequency identification tag.
International Journal of Mechanical Engineering and Robotics Research
The development and fabrication of stretchable printed electronics have been thoroughly investigated in several research studies; as they present an attractive solution for low-cost electronics. A special interest has been given to the implementation of these electronics in healthcare applications. This is due to their ability to sustain relatively high strain. Inkjet printing is an emerging technique which is used for the fabrication of printed electronics. Several research efforts have been invested in investigating the effect of varying several inkjet printing parameters on the performance of the fabricated stretchable circuits. In this paper, we particularly investigate the effect of the number of inkjet-printed silver nanoparticle layers on the axial breakdown strain of the stretchable circuits. That is the strain at which the circuit loses its electrical conductivity. Moreover, this study investigates the effect of the shape of the conductive pattern on the correlation between the number of layers and the breakdown strain. Two common shapes are examined: straight-line and horseshoe patterns. Results indicate that increasing the number of layers has an inverse effect on the maximum strain that the stretchable circuit can sustain. The same result is obtained for both investigated patterns.
Stretchable electronics based on Ag-PDMS composites
Scientific Reports, 2014
Patterned structures of flexible, stretchable, electrically conductive materials on soft substrates could lead to novel electronic devices with unique mechanical properties allowing them to bend, fold, stretch or conform to their environment. For the last decade, research on improving the stretchability of circuits on elastomeric substrates has made significant progresses but designing printed circuit assemblies on elastomers remains challenging. Here we present a simple, cost-effective, cleanroom-free process to produce large scale soft electronic hardware where standard surface-mounted electrical components were directly bonded onto all-elastomeric printed circuit boards, or soft PCBs. Ag-PDMS tracks were stencil printed onto a PDMS substrate and soft PCBs were made by bonding the top and bottom layers together and filling punched holes with Ag-PDMS to create vias. Silver epoxy was used to bond commercial electrical components and no mechanical failure was observed after hundreds of stretching cycles. We also demonstrate the fabrication of a stretchable clock generator.
Flexible and Printed Electronics, 2017
Stretchable conducting traces are the key component to realize wearable healthcare electronics; a conductor material that can withstand high strain conditions can be crucial. Here, we describe a simple fabrication pathway to achieve stretchable conductive ink for printing. Specifically, silver flakes and fluorine rubber are amalgamated by the aid of triethanolamine (TEA), which enhanced the compatibility of the components in solution state where methylisobutylketone is the co-solvent. Moreover, TEA plasticizes the composites after the printing and drying of the solvent, causing the composite to deform freely without losing conductivity. The composite exhibits a conductivity value of 8.49 × 10 4 S m −1 at rest. The printed composite itself is not mechanically resilient after plastic deformation, but it has remarkable adhesion on elastomeric substrates. Thus, the printed ink on elastomers allows stretchable trace that can accommodate repeated stretching/releasing cycles. We fabricate and characterize stretchable printed antenna with three different designs (loop, patch, and bowtie) for the application of skin-adhesive electronics.
The Influence of Geometrical Dimensions on Electromechanical Performance in Stretchable Circuit
Journal of Physical Science
Stretchable conductive ink (SCI) had been extensively studied for fabricating stretchable electronic devices. In this study, silver conductive ink and thermoplastic polyurethane (TPU) were used as substrate. The ink was printed on the substrate using screen printing with different shaped patterns varied by the widths of 1 mm, 2 mm and 3 mm: (a) straight, (b) zigzag , (c) square and (d) sinusoidal. The measurement of resistance was performed using four-point measurement during unloaded and loaded conditions of the shape pattern. This study revealed that width had influenced the resistivity in all shape patterns, where the narrow the width, the higher the resistance is. Comparative studies of electromechanical analysis of the shaped patterns had showed that a 3 mm width of zigzag pattern had a better electromechanical performance by having stretchability to maximum of 7.78%. Straight and square shape patterns, however, exhibited the poor tolerate deformation as both failed to conduct electricity upon straining at the minimum elongation of 1.11%.
Design and operation of silver nanowire based flexible and stretchable touch sensors
Journal of Materials Research, 2015
In recent years wearable devices have attracted significant attention. Flexibility and stretchability are required for comfortable wear of such devices. In this paper, we report flexible and stretchable touch sensors with two different patterns (interdigitated and diamond-shaped capacitors). The touch sensors were made of screen-printed silver nanowire electrodes embedded in polydimethylsiloxane. For each pattern, the simulation-based design was conducted to choose optimal dimensions for the highest touch sensitivity. The sensor performances were characterized as-fabricated and under deformation (e.g., bending and stretching). While the interdigitated touch sensors were easier to fabricate, the diamond-shaped ones showed higher touch sensitivity under as-fabricated, stretching or even bending conditions. For both types of sensors, the touch sensitivity remained nearly constant under stretching up to 15%, but varied under bending. They also showed robust performances under cyclic loading and against oxidation.
Highly Stretchable Electrodes on Wrinkled Polydimethylsiloxane Substrates
Scientific reports, 2015
This paper demonstrates a fabrication technology of Ag wrinkled electrodes with application in highly stretchable wireless sensors. Ag wrinkled thin films that were formed by vacuum deposition on top of pre-strained and relaxed polydimethylsiloxane (PDMS) substrates which have been treated using an O2 plasma and a surface chemical functionalization process can reach a strain limit up to 200%, while surface adhesion area can reach 95%. The electrical characteristics of components such as resistors, inductors and capacitors made from such Ag conductors have remained stable under stretching exhibiting low temperature and humidity coefficients. This technology was then demonstrated for wireless wearable electronics using compatible processing with established micro/nano fabrication technology.
Needs and Enabling Technologies for Stretchable Electronics Commercialization
MRS Advances, 2017
Stretchable electronics represent an emerging class of devices that can be compressed, twisted and conform to very complicated shapes. The mechanical and electrical compliances of the technology promise to open up applications for healthcare, energy and entertainment purposes. However, advancement in the field has been hindered by material related constraints. Moreover, the current microfabrication facilities are optimized for rigid substrates such as silicon, which have significant different properties compared to elastomers. In this paper, four categories of enabling technologies for stretchable electronics commercialization are critically reviewed, namely: the novel design of stretchable structures, use of non-conventional materials, state-of-art printing techniques and also the patterning of electrodes or metal interconnects via conventional manufacturing techniques.