Printed Electronics as Prepared by Inkjet Printing

Phung

Adv Materials Technologies

et al. 2020

This study presents a new fabrication method for touch screen sensors using inexpensive, flexible, and transparent polyethylene terephthalate (PET) films. In the proposed method, a transparent capacitive touch sensor array is implemented with two independent axes of invisible electrodes consisting of indium tin oxide (ITO) patterns and bridge electrodes. A low‐cost implementation of the bridge electrodes is achieved by using near‐field electrospinning (NFES) method for the conductive lines with linewidth of 3–5 µm. Then, the printed bridge electrode is sintered using green laser without damaging the PET film. It is demonstrated that two transparent electrodes deposited on a single sheet of PET film can detect the touch location by scanning the driving signal while simultaneously measuring the capacitances from the sensing lines connected via bridge electrodes.

Section: Figurementioning

confidence: 99%

Low‐Cost Fabrication Method for Thin, Flexible, and Transparent Touch Screen Sensors

Phung

Adv Materials Technologies

et al. 2020

“…This process builds up patterns and structures droplet by droplet, due to the high accuracy, reproducibility, and control of the volume of each droplet and the deposition area. Major challenges center around the formulation of functional inks with printable viscosity (1-30 cP) and surface tension (20-40 dynes/cm) to overcome the forces at the nozzle during ejection, the utilization of particles below 200 nm to avoid nozzle blockages, and the selection of solvents for adhesion and uniform film formation (Hutchings and Martin, 2018;Beedasy and Smith, 2020). Nonetheless, the high-resolution, versatility, and freedom of design deems inkjet printing a simple, readily accessible, lowcost patterning alternative to photolithographic methods, opening up a huge research window for prototyping and mass-producing electronics in future applications including personalized medicine, e-textiles, wearables, and disposable electronics at a much faster rate (Gao et al, 2017).…”

Section: Fabricationmentioning

confidence: 99%

Flexible Electronics: Status, Challenges and Opportunities

2020

The concept of flexible electronics has been around for several decades. In principle, anything thin or very long can become flexible. While cables and wiring are the prime example for flexibility, it was not until the space race that silicon wafers used for solar cells in satellites were thinned to increase their power per weight ratio, thus allowing a certain degree of warping. This concept permitted the first flexible solar cells in the 1960s (Crabb and Treble, 1967). The development of conductive polymers (Shirakawa et al., 1977), organic semiconductors, and amorphous silicon (Chittick et al., 1969; Okaniwa et al., 1983) in the following decades meant huge strides toward flexibility and processability, and thus these materials became the base for electronic devices in applications that require bending, rolling, folding, and stretching, among other properties that cannot be fulfilled by conventional electronics (Cheng and Wagner, 2009) (Figure 1). Presently there is great interest in new materials and fabrication techniques which allow for highperformance scalable electronic devices to be manufactured directly onto flexible substrates. This interest has also extended to not only flexibility but also properties like stretchability and healability which can be achieved by utilizing elastomeric substrates with strong molecular interactions (Oh et al., 2016; Kang et al., 2018). Likewise, biocompatibility and biodegradability has been achieved through polymers that do not cause adverse effect to the body and can be broken down into smaller constituent pieces after utilization (Bettinger and Bao, 2010; Irimia-Vladu et al., 2010; Liu H. et al., 2019). This new progress is now enabling devices which can conform to complex and dynamic surfaces, such as those found in biological systems and bioinspired soft robotics. These next-generation flexible electronics open up a wide range of exciting new applications such as flexible lighting and display technologies for consumer electronics, architecture, and textiles, wearables with sensors that help monitor our health and habits, implantable electronics for improved medical imaging and diagnostics, as well as extending the functionality of robots and unmanned aircraft through lightweight and conformable energy harvesting devices and sensors. While conventional electronics are very capable of these functions, flexible electronics are intended to expand the mechanical features to adhere to novel form factors through hybrid strategies, or as standalone solutions where the application does not require high computation power, intended to be highly robust to deformation, low cost, thin, or disposable. The definition of flexibility differs from application to application. From bending and rolling for easier handling of large area photovoltaics, to conforming onto irregular shapes, folding, twisting, stretching, and deforming required for devices in electronic skin, all while maintaining device performance and reliability. While early progress and many important innovations have alre...

“…Today's fast-growing electronic market demands the development of cost-efficient, customizable yet mass-producible and environmentally friendly electrical components. Most additive manufacturing methods, particularly inkjet printing, have the potential to meet these requirements, provided that eco-friendly materials are used [1]. The additive manufacturing of 2.5D (the expansion in one of three main spatial directions is much smaller) electronics structures is commonly referred to as printed electronics (PE).…”

Section: Introductionmentioning

confidence: 99%

“…For many applications, such as resistive sensing elements, it is crucial that the connection does not only provide good conductivity but also has high reproducibility [43][44][45]. Furthermore, especially in inkjet printing, the resulting layer is only a few µm thick, or even lies in the sub-µm range [1,46], which can be considered as quite thin compared to other frequently employed printing techniques, such as screen printing (typical layer thickness: beyond 10 µm [47]). This fact creates new challenges, as the printed layer might be easily damaged during contacting, either due to the high temperature when soldering or due to mechanical forces.…”

Section: Introductionmentioning

confidence: 99%

“…(a) Direct soldering on Mylar ® PET in some cases leads to poor contacting(1) or even ablation of the printed structures (2); (b) Contacting using adhesive bonding on two different samples on p_e:smart ® paper; (c) Soldering on Ag pads on p_e:smart ® -poor contacting due to damage of the printed layer; the scale bar corresponds to 1 mm; (d) Contacting using crimping on Kapton ® , the printed layer is destroyed during processing; the scale bar corresponds to 1 mm.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of Standard Electrical Bonding Strategies for the Hybrid Integration of Inkjet-Printed Electronics

Rauter

Zikulnig

Sinani

et al. 2020

Electronic Materials

Different conductive bonding strategies for the hybrid integration of flexible, inkjet-printed electronics are investigated. The focus of the present work lies on providing a practical guide comprising standard techniques that are inexpensive, easily implementable and frequently used. A sample set consisting of identical conductive test structures on different paper and plastic substrates was prepared using silver (Ag) nanoparticle ink. The sintered specimens were electrically contacted using soldering, adhesive bonding and crimping. Electrical and mechanical characterization before and after exposing the samples to harsh environmental conditions was performed to evaluate the reliability of the bonding methods. Resistance measurements were done before and after connecting the specimens. Afterwards, 85 °C/85% damp-heat tests and tensile tests were applied. Adhesive bonding appears to be the most suitable and versatile method, as it shows adequate stability on all specimen substrates, especially after exposure to a 85 °C/85% damp-heat test. During exposure to mechanical tensile testing, adhesive bonding proved to be the most stable, and forces up to 12 N could be exerted until breakage of the connection. As a drawback, adhesive bonding showed the highest increase in electrical resistance among the different bonding strategies.