The advances in the mass scale manufacturing of microscale energy storage devices via inkjet printing rely on the development of high-quality printable ink. The earth-abundant, non-toxic carbon materials such as graphene, carbon nanotube (CNT), reduced graphene oxide (r-GO) have shown excellent electrochemical performance and thus garnered significant interest as suitable electrode material. Here we report the formulation of printable graphene aerogel ink and the fabrication of the micro-supercapacitors (μ-SCs) on flexible polyimide substrates via inkjet printing method. The advantage of using pristine graphene aerogel intends to avoid the complex processing steps and the use of toxic chemicals in the ink formulation and lower the concentration of other additive components. Thus, a higher loading of active functional material in the printable ink is achieved. The aerogel ink directly employed to write the interdigitated μ-SCs devices on a flexible polyimide substrate at room temperature via inkjet printing. The electrochemical performance measured using the organic ionic liquid in the voltage range of 0-1 volt. These printed μ-SCs showed an areal capacity of 55 μF/cm2 at a current density of 6 micro-amp/cm2. The printed devices showed good stability, with ~80% of capacity retention after 10,000 cycles. Contrary to the graphene-based μ-SCs, the aerogel micro-supercapacitors do not show a significant distortion in the CV scan even at a very high scan rate of ~2Vs-1. Thus, we propose graphene aerogel as promising electrode material for mass-scale production of the μ-SCs.
Inkjet printable graphene inks are very attractive for applications in flexible and foldable electronics, such as wearable electronics and the Internet of Things. However, the ink preparation is still very time consuming as high concentrations can be achieved only with prolonged sonication (>24 hours) or with expensive setups. Here we demonstrate a water-based inkjet printable ink made from electrochemically exfoliated graphene. A printable and stable (> 1 month) ink with concentration of ~2.25 mg mL-1 was formulated in less than 5 hrs, using two successive steps: first exfoliation and dispers…
Inkjet-printed wearable electronic textiles (e-textiles) are considered to be very promising due to excellent processing and environmental benefits offered by digital fabrication technique. Inkjet-printing of conductive metallic inks such as silver (Ag) nanoparticles (NPs) are well-established and that of graphene-based inks is of great interest due to multi-functional properties of graphene-based materials. However, poor ink stability at higher graphene concentration and the cost associated with the higher Ag loading in metal inks have limited their wider use. Moreover, graphene-based e-texti…
We report the fabrication of a low cost, and highly reproducible large scale surface-enhanced Raman spectroscopy substrate using an inkjet-printed Ag nanoparticle ink (AgNI). The AgNI SERS substrates were evaluated for SERS using BPY as a molecular probe. The printed AgNI dot arrays exhibit an excellent SERS performance and reproducibility. The batch to batch and spot to spot standard deviation value of less than 10 percent was obtained. The results reveal the reproducibility of the AgNI SERS dot arrays and its potential application for SERS substrates.
We present an investigation of inkjet printed strain gauges based on two-dimensional (2D) materials. The technology leverages water-based and biocompatible inks to fabricate strain measurement devices on flexible substrates such as paper. We demonstrate that the device performance and sensitivity are strongly dependent on the printing parameter (i.e., drop- spacing, number of printing passes, etc.). We show that values of the Gauge Factor up to 125 can be obtained, with large sensitivity (>20%) even when small strains (0.3%) are applied. Furthermore, we provide preliminary examples of heterost…
Currently, additive manufacturing of ceramics by stereolithography (SLA) is limited to single materials and by a poor thickness resolution that strongly depends on the ceramic particles-UV light interaction. Combining selective laser curing with inkjet printing represents a novel strategy to overcome these constrains. Nonetheless, this approach requires UV-curable inks that allow hardening of the printed material and sintering to high density. In this work, we report how to design an ink for inkjet printing of yttria stabilized zirconia (YSZ) which can be impressed by addition of UV-curable mo…
Inkjet printing of 8% Y2O3-stabilized ZrO2 (YSZ) thin films is achieved by designing a novel water-based reactive ink for Drop-on-Demand (DoD) inkjet printing. The ink formulation is based on a novel chemical strategy that consists of a combination of metal oxide precursors (zirconium alkoxide and yttrium salt), water and a nucleophilic agent, i.e. n-methyldiethanolamine (MDEA). This chemistry leads to metal-organic complexes with long term ink stability and high precision printability. Ink rheology and chemical reactivity are analyzed and controlled in terms of metal-organic interactions in t…
Heterostructures constructed from two-dimensional building blocks have shown promise for field-effect transistors, memory devices, photosensors and other electronic applications1,2. 2D nanosheet crystals can be constructed into multilayer heterostructures using layer-by-layer methods3, but that method cannot be used to fabricate large-scale and thick heterostructures, due to the time-consuming nature and low efficiency of the process. An alternative approach to deposit different two-dimensional materials is by inkjet printing4-7. Here we show the fabrication of a nanosheet supercapacitor by in…
Water dispersion of nanometric yttria stabilized zirconia (YSZ) particles synthesized by continuous hydrothermal synthesis are transferred into nanoinks for thin film deposition. YSZ nanoparticles are synthesized in supercritical conditions resulting in highly dispersed crystals of 10 nm in size. The rheology of the colloid is tailored to achieve inkjet printability (Z) by using additives for regulating viscosity and surface tension. Inks with a wide range of properties are produced. A remarkable effect of nanoparticles on the ink printability is registered even at solid load < 1% vol. In part…
We report fabrication of optical waveguides embedded in oxidised porous silicon in a mask-less process. Patterned pore-filling was attained by means of inkjet printing, enabling lateral modification of the waveguide's index of refraction and other optical properties thus providing full two-dimensional refractive index control of the optical waveguide. The waveguides were created by applying a KDP salt solution over a porous silicon film by means of a material printer. Light guiding was demonstrated at wavelengths 1.064 and 1.550 microns. Measured values of the intensity attenuation at these wa…
Kapton HN films, adopted worldwide due to their superior thermal durability (up to 400 °C), allow the high temperature sintering of nanoparticle based metal inks. By carefully selecting inks and Kapton substrates, outstanding thermal stability and anti-delaminating features are obtained in both aqueous and organic solutions and were applied to four novel devices: a solid state ion selective nitrate sensor, an ssDNA based mercury aptasensor, a low cost protein sensor, and a long lasting organic thin film transistor (OTFT). Many experimental studies on parameter combinations were conducted durin…
The availability of graphene and related two-dimensional (2D) crystals in ink form, with on demand controlled lateral size and thickness, represents a boost for the design of printed heterostructures. Here, we provide an overview on the formulation of functional inks and the current development of inkjet printing process enabling the realization of 2D crystal-based heterostructures.
A well-defined insulating layer is of primary importance in the fabrication of passive (e.g. capacitors) and active (e.g. transistors) components in integrated circuits. One of the most widely known 2-Dimensional (2D) dielectric materials is hexagonal boron nitride (hBN). Solution-based techniques are cost-effective and allow simple methods to be used for device fabrication. In particular, inkjet printing is a low-cost, non-contact approach, which also allows for device design flexibility, produces no material wastage and offers compatibility with almost any surface of interest, including flex…
The miniaturization of energy storage units is pivotal for the development of next-generation portable electronic devices. Micro-supercapacitors (MSCs) hold a great potential to work as on-chip micro-power sources and energy storage units complementing batteries and energy harvester systems. The scalable production of supercapacitor materials with cost-effective and high-throughput processing methods is crucial for the widespread application of MSCs. Here, we report wet-jet milling exfoliation of graphite to scale-up the production of graphene as supercapacitor material. The formulation of aqu…
The surface properties of a substrate are among the most important parameters in the printing technology of functional materials, determining not only the printing resolution but also the stability of the printed features. This paper addresses the wetting difficulties encountered during inkjet printing on homogeneous substrates as a result of improper surface properties. We show that the wetting of a substrate and, consequently, the quality of the printed pattern, can be mediated through the deposition of polymeric layers that are a few nanometers thick. The chemical nature of the polymers det…
Two-dimensional (2D) materials, such as graphene, are seen as potential candidates for fabricating electronic devices and circuits on flexible substrates. Inks or dispersions of 2D materials can be deposited on flexible substrates by large-scale coating techniques, such as inkjet printing and spray coating. One of the main issues in coating processes is nonuniform deposition of inks, which may lead to large variations of properties across the substrates. Here, we investigate the role of surface morphology on the performance of graphene ink deposited on different paper substrates with specific …
-This paper presents an inkjet printing capacitive microwave sensor for toxic vapor detection. The designed sensors were presented and fabricated with success. The experiments show sensitivity to ethanol vapor according to the S parameters. It is equal to 0.9 kHz/ppm and 1.3 kHz/ppm for the sensors based on 5 and 50 sensitive layers respectively. This sensor will be integrated into real-time multi-sensing platforms adaptable for the Internet of Things (IoT).
There is growing interest in transitioning electronic components and circuitry from stiff and rigid substrates to more flexible and stretchable platforms, such as thin plastics, textiles, and foams. In parallel, the push for more sustainable, biocompatible, and cost-efficient conductive inks to coat these substrates, has led to the development of formulations with novel nanomaterials. Among these, 2D materials, and particularly graphenes and MXenes, have received intense research interest due to their increasingly facile and scalable production, high electrical conductivity, and compatibility …
Paper is the ideal substrate for the development of flexible and environmentally sustainable ubiquitous electronic systems, which, combined with two-dimensional materials, could be exploited in many Internet-of-Things applications, ranging from wearable electronics to smart packaging. Here we report high-performance MoS2 field-effect transistors on paper fabricated with a channel-array approach, combining the advantages of two large-area techniques: chemical vapor deposition and inkjet-printing.The first allows the pre-deposition of a pattern of MoS2; the second, the printing of dielectric lay…
