Towards printed magnetic sensors based on organic diodes

We report the study of magnetotransport properties of regio-regular poly (3-hexyl thiophene) based organic diodes. The devices were fabricated using two different techniques of spin coating and inkjet printing. Positive magnetoresistance (MR) effect was observed at room temperature in all the devices. The highest MR magnitude reached up to 16% for some spin-coated devices and up to 10% in inkjet printed devices. The MR magnitude and line shapes were found to depend strongly on the measuring current. We observed deviation from the theoretically predicted Lorentzian or non-Lorentzian line shape of the MR traces, which is discussed in detail in the article. Although, the printed devices exhibit MR response as high as for the spin coated ones, they still need to be optimized in terms of performance and yield for large scale applications as magnetic sensors

Application of Paper-Supported Printed Gold Electrodes for Impedimetric Immunosensor Development

Peer reviewe

Inkjet printed paper based frequency selective surfaces and skin mounted RFID tags: the interrelation between silver nanoparticle ink, paper substrate and low temperature sintering technique

Inkjet printing of functional frequency selective surfaces (FSS) and radio frequency identification (RFID) tags on commercial paper substrates using silver nanoparticle inks sintered using low temperature thermal, plasma and photonic techniques is reported. Printed and sintered FSS devices demonstrate performances which achieve wireless communication requirements having a forward transmission scattering parameter, S21, depth greater than ?20 dB at 13 GHz. Printed and plasma sintered RFID tags on transfer paper, which are capable of being mounted on skin, improved read distances compared to previously reported single layer transfer RFID tags fabricated by conventional thermal sintering

Mechanical Drawing of Gas Sensors on Paper

Pencil it in: Mechanical abrasion of compressed single-walled carbon nanotubes (SWCNTs) on the surface of paper produces sensors capable of detecting NH[subscript 3] gas at sub-ppm concentrations. This method of fabrication is simple, inexpensive, and entirely solvent-free, and avoids difficulties arising from the inherent instability of many SWCNT dispersions.Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (W911NF-07-D-004)National Institutes of Health (U.S.) (National Cancer Institute (U.S.) Postdoctoral Fellowship Grant F32A1571997

Micro-drilling of polymer tubular ultramicroelectrode arrays for electrochemical sensors

sensor

3-dimensional inkjet printing of macro structures from silver nanoparticles

The adoption of additive manufacturing technology is gaining interest for processing precious metals. In this study, the capability of inkjet printing was explored to fabricate macroscopic parts from commercial silver nanoparticle ink (AgNPs). A bespoke JETx® three dimensional (3D) inkjet printing machine was used to print and subsequently sinter up to 1000 layers of AgNPs using an infrared source. Examination of the sample using X-ray computed tomography and scanning electron microscopy revealed the existence of both micro- and nano-scale pores within the structure. Pinning effect, residual surface temperature, insufficient droplet overlap and surface defects were the key factors contributing to the voids. Elemental mapping confirmed the structure to be composed of 87% of silver along with carbon and oxygen. The 750 dpi sample showed a 25% reduction in nanopores and 77% lower micro-pores compared to the 600 dpi sample. In terms of hardness, the 750 dpi sample was 29% harder than the 600 dpi sample, showcasing samples with higher print resolution can contribute towards less voids and improved mechanical properties. Thus by demonstrating the possibility to fabricate dense parts from AgNPs using inkjet technology, this study opens a novel route for processing nano-scale particulates and precious metals in 3D

Hand-drawn resistors, capacitors, diodes, and circuits for a pressure sensor system on paper

Hand-written fabrication techniques offer new ways of developing customizable, biodegradable and low-cost electronic systems. In this work, a new level of complexity is demonstrated for hand-written electronics by fabricating passive components, circuits and a sensorsystem on paper. The system comprises a pencil-written graphite force-sensitive-resistor, a pencil-drawn RC-filter, a pen-written half-wave rectifier, and a commercial front-end voltage amplifier. The sensor system exhibits a linear response for pressures up to 1.2 kPa, and a sensitivity of 51 mV kPa-1 . Furthermore, the electrical and mechanical performance of the single components and circuits is studied. Diodes fabricated through pen-written deposition of silver and nickel contacts on amorphous Indium-Gallium-Zinc-Oxide coated paper show rectification ratios up to 1:8. Tensile and compressive bending measurements applied to all pencil-written components for radii down to 0.1 mm indicate minor influence of strain. Similar results are obtained for circuits created from these individual components. Diodes and half-wave rectifiers show a stable behavior when bent to a radius of 5 mm. The presented techniques can enable the development of flexible and eco-friendly wearables and sensors for consumer and healthcare applications, and are an effective way for school-pupils to explore the world of electronics

Foldable Conductive Cellulose Fiber Networks Modified by Graphene Nanoplatelet-Bio-Based Composites

Truly foldable flexible electronic components require a foldable substrate modified with a conducting material that can retain its electrical conductivity and mechanical integrity even after hard mechanical manipulations and multiple folding events. Here, such a material exploiting the combination of all-biodegradable components (substrate and the polymer matrix) and graphene nanoplatelets is designed and fabricated. A commercially available thermoplastic starch-based polymer (Mater-Bi) and graphene nanoplatelets are simultaneously dispersed in an organic solvent to formulate conductive inks. The inks are spray painted on pure cellulose sheets and hot-pressed into their fiber network after drying. The resultant nanostructured flexible composites display excellent isotropic electrical conductivity, reaching very low sheet resistance value ≈10 Ω sq−1, depending on the relative concentration between the biopolymer and the graphene nanoplatelets. Transmission electron microscopy results indicated that during hot-pressing, graphene nanoplatelets are physically embedded into the cellulose fibers, resulting in high electrical conductivity of the flexible composite. The paper-like flexible conductors can withstand many severe folding events, maintaining their mechanical and electrical properties and showing only a slight decrease of their electrical conductivity with respect to the unfolded counterparts. Unlike conductive paper technologies, the proposed paper-like flexible conductors demonstrate both sides isotropic conductivity due to pressure-induced impregnation

3D inkjet printing of electronics using UV conversion

The production of electronic circuits and devices is limited by current manufacturing methods that limit both the form and potentially the performance of these systems. Additive Manufacturing (AM) is a technology that has been shown to provide cross sectoral manufacturing industries with significant geometrical freedom. A research domain known as Multi-Functional Additive Manufacturing (MFAM) in its infancy looks to couple the positive attributes of AM with application in the electronics sector could have a significant impact on the development of new products, however there are significant hurdles to overcome. This paper reports on the single step MFAM of three dimensional (3D) electronic circuitry within a polymeric structure using a combination of conductive and non-conductive materials within a single material jetting based AM system. The basis of this breakthrough is a study of the optical absorption regions of a silver nanoparticle (AgNP) conductive ink which lead to a novel method to rapidly process and sinter silver nanoparticle inks in ambient conditions using simple UV radiation contemporaneously with UV-curing of deposited polymeric structures