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The multi-drop method with a good droplet quality is a big challenge in inkjet technology. In this study, optimization of Drop on Demand (DoD) inkjet printer waveform design was conducted. The effectiveness of the waveform design, so-called W waveform, from previous study as a preliminary vibration for the multi-drop ejection method was investigated. The unmodified W waveform was proven not to be an effective waveform for lower viscosity of liquid, especially when compared by the standard waveform obtained from a print-head manufacturer. Edible ink with a viscosity below the optimum range for print-head specifications was employed as the operating liquid. The preliminary vibration W waveform was modified to improve the droplet quality of the edible ink. It was proven that a 40% adjusted voltage of the rear wave of the W waveform was effective as the optimum waveform design for edible ink. The droplet quality of the multi-drop ejection method for grey-scale technology was improved by optimizing the W waveform design.

The altered document identification proficiency test of the China National Accreditation Service for Conformity Assessment (CNAS), initiated by the China Academy of Forensic Science in 2022, provided a specially prepared questioned document sample. This challenging case sample rendered conventional morphological examination methods virtually ineffective. As a result, only a low percentage of judicial appraisal institutions received the “satisfactory” rating. This work examined the characteristics of the inkjet printers used in the proficiency test from two independent perspectives, by combining volatile solvent composition analysis of printing inks using GC–MS creatively with conventional morphological examination. This work not only efficiently determined whether there was appended content via a secondary printing pass in the case sample, but also further identified the brands of the inkjet printers used to prepare the sample of the proficiency test. Finally, precautions for identifying the brands of inkjet printers were summarized. We hope this work will underscore the importance of incorporating physical and chemical analytical methods in questioned document examination and draw forensic examiners’ attention to its necessity. •Presents results of China Academy of Forensic Science 2022 altered document proficiency test.•Combined chemical and morphological analysis improves robustness.•GC–MS analysis of volatile solvents recommended and demonstrated.•Discusses limitations of morphological methods under current training system.

Conducting polymer hydrogels represent a unique class of materials that synergizes the advantageous features of hydrogels and organic conductors and have been used in many applications such as bioelectronics and energy storage devices. They are often synthesized by polymerizing conductive polymer monomer within a nonconducting hydrogel matrix, resulting in deterioration of their electrical properties. Here, we report a scalable and versatile synthesis of multifunctional polyaniline (PAni) hydrogel with excellent electronic conductivity and electrochemical properties. With high surface area and three-dimensional porous nanostructures, the PAni hydrogels demonstrated potential as high-performance supercapacitor electrodes with high specific capacitance (∼480 F·g ⁻¹), unprecedented rate capability, and cycling stability (∼83% capacitance retention after 10,000 cycles). The PAni hydrogels can also function as the active component of glucose oxidase sensors with fast response time (∼0.3 s) and superior sensitivity (∼16.7 μA·mM ⁻¹). The scalable synthesis and excellent electrode performance of the PAni hydrogel make it an attractive candidate for bioelectronics and future-generation energy storage electrodes.

Organic/quantum dot light-emitting diode displays have recently been manufactured using inkjet printers, which require stable ink drops and strict control during the printing process. Combining Ansys Fluent and Ansys Mechanical simulations, this research establishes the conditions that stabilize the ink droplets. The feasibility of this approach is verified through a jetting simulation of Newtonian fluids with almost constant viscosity and a comparison of the simulation and experimental results. Then, a commercial non-Newtonian ink with a shear-rate-dependent viscosity is simulated, and the simulation and experimental results are again compared. The study then evaluates why the experimental and simulation outcomes of non-Newtonian fluids differ under the same voltage conditions. Besides finding the stable drop conditions, the performed inkjet simulations reveal the pressure changes in the inkjet nozzle.

New manufacturing technologies under the banner of rapid prototyping enable the fabrication of structures close in architecture to biological tissue. In their simplest form, these technologies allow the manufacture of scaffolds upon which cells can grow for later implantation into the body. A more exciting prospect is the printing and patterning in three dimensions of all the components that make up a tissue (cells and matrix materials) to generate structures analogous to tissues; this has been termed bioprinting. Such techniques have opened new areas of research in tissue engineering and regenerative medicine.

Carbon-based materials, including graphene, single walled carbon nanotubes (SWCNTs), and multi walled carbon nanotubes (MWCNTs), are very promising materials for developing future-generation electronic devices. Their efficient physical, chemical, and electrical properties, such as high conductivity, efficient thermal and electrochemical stability, and high specific surface area, enable them to fulfill the requirements of modern electronic industries. In this review article, we discuss the synthetic methods of different functionalized carbon materials based on graphene oxide (GO), SWCNTs, MWCNTs, carbon fibers (CFs), and activated carbon (AC). Furthermore, we highlight the recent developments and applications of functionalized carbon materials in energy storage devices (supercapacitors), inkjet printing appliances, self-powered automatic sensing devices (biosensors, gas sensors, pressure sensors), and stretchable/flexible wearable electronic devices.

In this article, an inkjet-printed circular-shaped monopole ultra-wideband (UWB) antenna with an inside-cut feed structure was implemented on a flexible polyethylene terephthalate (PET) substrate. The coplanar waveguide (CPW)-fed antenna was designed using ANSYS high-frequency structural simulator (HFSS), which operates at 3.04–10.70 GHz and 15.18–18 GHz (upper Ku band) with a return loss < −10 dB and a VSWR < 2. The antenna, with the dimensions of 47 mm × 25 mm × 0.135 mm, exhibited omnidirectional radiation characteristics over the entire impedance bandwidth, with an average peak gain of 3.94 dBi. The simulated antenna structure was in good agreement with the experiment’s measured results under flat and bending conditions, making it conducive for flexible and wearable Internet of things (IoT) applications.

A major obstacle to the development of organic transistors for large-area sensor, display, and circuit applications is the fundamental compromise between manufacturing efficiency, transistor performance, and power consumption. In the past, improving the manufacturing efficiency through the use of printing techniques has inevitably resulted in significantly lower performance and increased power consumption, while attempts to improve performance or reduce power have led to higher process temperatures and increased manufacturing cost. Here, we lift this fundamental limitation by demonstrating subfemtoliter inkjet printing to define metal contacts with single-micrometer resolution on the surface of high-mobility organic semiconductors to create high-performance p-channel and n-channel transistors and low-power complementary circuits. The transistors employ an ultrathin low-temperature gate dielectric based on a self-assembled monolayer that allows transistors and circuits on rigid and flexible substrates to operate with very low voltages.

One of the challenges in inkjet technology is the reduction of residual vibration and crosstalk that can result in the appearance of satellites and ligaments in the produced droplets, which affects the overall printing quality. This study evaluated the print quality produced by comparing basic waveform with several actuating waveforms, particularly in the application of the grayscale method or the multi-pulse-ejection method. Print quality was compared using a microscope to evaluate the appearance of ejected droplet on a printing surface. This study measured aspect ratio to illustrate the circularity of the droplets. Based on the findings in this study, the waveform design with adjustments made to the rear wave from the preliminary vibration is proved effective in improving print quality. The average of aspect ratio obtained approached 1, means almost perfect circular, which was 0.997, with the lowest standard deviation of 0.0151. Our paper examines how a specific type of inkjet printer, using a spesific waveform design, impacts print quality. By optimizing the waveform used to eject ink droplets, we aim to enhance the clarity, accuracy, and overall visual appeal of printed materials. This research has broader implications for industries relying on high-quality printing, such as graphic design, packaging, and photography. By improving print quality, we can elevate the aesthetic appeal and effectiveness of various printed materials in everyday life, from product labels to marketing materials. This study contributes to advancing printing technology, ultimately benefiting consumers and businesses alike by delivering better quality printed products.