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3D printing of antennas on removable fingernail for on-body communications at microwave and millimetre waves is proposed. Aerosol Jet technology, a fine-feature material deposition solution, has been used to directly print microstrip patch antennas on an acrylonitrile butadiene styrene (ABS) removable finger nail substrate. Two antennas have been printed and assessed, one operating at 15 GHz and the other at 28 GHz. Nanoparticle conductive silver ink has been employed to create the microstrip patch antennas and corresponding transmission line using an Optomec machine. The inks are then cured using a PulseForge machine. A further copper layer is added to the millimeter wave antenna via an electroplating process. The antennas have been simulated and measured off-the-finger and on-the-finger. Simulated and measured reflection coefficients (S11 ) and radiation patterns are found to be in good agreement. The proposed on-body antennas can find application in the Internet of Things (IoT) where large amount of sensing data can be shared at the microwave and millimetre wave spectrum of future 5G communications. The removable finger nails could include other electronic devices such as on-body sensors, computational, storage and communication systems.

Despite the low cost and easy fabrication afforded by 3D printing technology, high dielectric loss of the 3D printing filament degrades the performance of 3D printed radio frequency electronics at high frequencies. In this paper, we propose a 3D-printed substrate-integrated waveguide (SIW) using a lossy polylactic acid or polylactide (PLA) filament. To minimize the insertion loss of the SIW, a non-uniform honeycomb is 3D-printed as the dielectric material of the SIW. The non-uniform honeycomb-shaped substrate is composed of large unit cells, which achieve low insertion loss (0.01 dB/mm) because of the low volume of the dielectric material. The performance characteristics of the proposed SIW is compared with those of SIWs made of solid and uniform honeycomb-shaped structures. The average insertion loss of the microstrip line-fed SIW with the proposed non-uniform honeycomb substrate is 0.92 dB in the frequency range of 1.97 to 3.35 GHz and those of the solid PLA and uniform honeycomb substrates are 2.49 dB and 1.38 dB, respectively. The proposed 3D-printed SIW additionally has the advantages of light weight and low cost.

This work investigates the use of substrate integrated waveguide fed open slot antenna (WOSA) in an array for the first time to provide a new SIW slot antenna array with wide bandwidth and single-layer structure. The antenna array consists of 4×2 substrate integrated WOSA elements as a radiating part and two 1-to-4 SIW power dividers as the feeding network. The whole array is differentially fed and built on a single-layered laminate. To demonstrate the wideband performance of the substrate integrated WOSA elements, two sets of feeding networks designed at different frequencies are used to feed the same radiating part. In this way, a V-band and a W-band array were built. Both the antenna arrays were fabricated and measured. Benefiting from the excellent performance of the substrate integrated WOSA elements, the antenna array achieves a wide bandwidth of 32.3% (54.0 to 74.8 GHz) with a peak gain varies from 11.3 to 15.6 dBi. It has been demonstrated that the substrate integrated WOSA array can achieve a wide bandwidth with a single-layer structure, which is attractive for millimeter-wave applications.

This paper presents a smart sensor patch with flexible strain sensor and a printed temperature sensor integrated with a Near Field Communication (NFC) tag to detect strain or temperature in a semi-quantitative way. The strain sensor is fabricated using conductive polymer poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) in a polymer Polydimethylsiloxane microchannel. The temperature sensor is fabricated by printing silver electrodes and PEDOT:PSS on a flexible polyvinyl chloride (PVC) substrate. A customdeveloped battery-less NFC tag with an LED indicator is used to visually detect the strain or temperature by modulating the LED light intensity. The LED shows maximum brightness for relaxed or no strain condition, and also in the case of maximum temperature. In contrast, the LED is virtually off for the maximum strain condition and for room temperature. Both these could be related to food spoilage. Swollen food packages can be detected with the strain sensor, serving as beacons of microbial contamination. Temperature deviations can result in the growth or survival of food-spoilage bacteria. Based on this, the potential application of the sensor system for smart food packaging is presented.

In this study, two designs were proposed for a gold electrochemical device. Both were fabricated using a single mask photolithography process and electrochemically characterized. The best design (device) was further used to integrate the sulfur-doped graphene (S-Gr), as sensing layer for the electrochemical determination of ascorbic acid. The gold WE acted as a very good substrate for the immobilization of S-Gr.

A new method of bonding the solid photoresist film is proposed for improving the thickness uniformity on the chip substrate. The water-soluble polymer supports the resist film and is dissolved before patterning. The chip area can be used up to the edge. The resist thickness demonstrated is 1.73 μm +/−1.2% in maximum deviation.

This paper presents a wideband planar steerable antenna array. The structure is composed of an 8x8 Butler matrix connected to an 8x1 antenna array. It is fabricated on an FR-4 substrate and operates at 3GHz. The disadvantage of the 8x8 Butler matrix is the small bandwidth. Therefore, this paper introduces the development of wideband components to enlarge the bandwidth of the structure resulting in a bandwidth of 1.26GHz. Moreover, the 8x8 Butler matrix to be presented in this work is special in comparison to the existing works in the literature because it permits reusing the 4x4 Butler matrix in the design. This operation is valuable in the industry since it reduces the effort and the cost of the production. The final structure uses wideband and miniaturized components on a single layer substrate which results in an economical, small size and wideband steerable antenna array.

In this paper, a measurement method for electromagnetic parameters of flexible materials based on air coaxial line in low frequency band is proposed. First a material with known electromagnetic parameters and smooth surface is selected as the substrate, the flexible material is attached to the substrate and loaded into the air coaxial line together. Then calibration kits open and short are connected to the terminal of the air coaxial line respectively, and the single-port reflection coefficient of the device is measured by vector network analyzer (VNA). Finally, the electromagnetic parameters of the flexible material are deduced based on the impedance of the specimens section in air coaxial line. Experimental results show that the method proposed in this paper is effective and reliable.

The Taguchi method was used to optimize the stack structure of electronic paper displays. The falling ball experiment was performed to analyze the effect of various combinations of cover lenses, optically clear adhesives, and substrates on the impact strength of the module surfaces. The results revealed that the stack structure considerably improved the surface impact resistance. The combination of a glass substrate electronic paper display and a plastic cover lens achieved the highest surface impact resistance.

Warpage of ball grid array substrate and printed circuit board is a common issue during reflow process due to the mismatch of coefficients of thermal expansion. With the development of the substrate becoming larger and larger, there is a higher risk of reflow defects caused by warpage. In this paper, an open soldering failure, head-in-pillow, caused by warpage is reported when ball grid array package was reflowed onto printed circuit board. Shadow moire technique was then used for dynamic warpage analysis on both sides of ball grid array substrate and printed circuit board. The dynamic warpage measurement results indicate that Al corner is the highest risk location for head-in-pillow failure, which matches that of actual head-in-pillow defect location very well. Design of experiment on reflow profile and stencil aperture design were conducted. Based on design of experiment results and considering the reflow process control window, medium temperature profile (U1 peak temperature of 240°C) with aperture design of the stencil 2 was chosen for manufacturing.

As Micro LED technology becomes increasingly matured, several assembly process options were proposed, and seems feasible and reliable to be used in mass production. Usually, these processes require a tacky flux to adhere the die to the substrate when mass transferring, and meanwhile to provide certain activation to facilitate the joining process. However, the work life of such flux is limited, which leads to low printing efficiency and unstable assembly quality. In this work, a novel inorganic compound stabilized tacky flux system was successfully developed for newly emerging carrier assistant Micro LED mass transfer technology. This designation can extend the working life from less than 30 mins to more than 180 mins. Such a significant improvement in working life was realized by introducing an inorganic stabilizer, which reacted with chemicals to strengthen the inner connection, furtherly realized precise and efficient tackiness in-situ controlling. Moreover, this tacky flux system didn't make any compromising on flux's inherent characteristic of promoting soldering. Inorganic compound stabilized tacky flux provided a new approach for material solutions in Micro LED mass transfer.

Today's flip chip scale packaging (FCCSP) microelectronics products are becoming more and more complex, especially in the packaging process using molded underfill manufacturing, which reduces the cost of flip chip technology such as molded underfill (MUF) High, provides molding ability in molding. The problem is to leave effective space under the chip. Generally speaking, this requires a lot of experimental DOE (chip size, substrate design, and epoxy resin type) to solve this problem. For the reasons mentioned above, mold-flow simulation software can be applied to use different flow condition to obtain the best solution as the MUF FCCSP of the substrate structure design. Such a simulation method can help shorten the product development cycle. This article uses the commonly used 3D molding process simulation software for transferring manufacturing process parameters. This article will introduce a comparison of two different structures. A MUF is FCCSP, it is matched with different bump height (SOH) structure comparison (control the flow of different chip bottom space), and observe the difference of the flow melt-front. The second is that there are two different designs on the surface of the substrate (welding masks with completely open or partially open patterns) through the table to enter the previously separated welding mask samples (welding masks with l0um depth structure) to maintain different modes. As this research, we can get a lot of conclusion that improve the molding capability of molded underfill FCCSP in the transfer molding process. If the bottom of the molded underfill FCCSP chip is matched with a structure with a height of 55 µm, then the molding epoxy can easily flow under the area with a large flow space, so the risk of entrapment can be reduced. In addition, the molding compound also has good melt front fluidity, and the fully open substrate surface design of the substrate solder resist layer can achieve more l0µmm space underneath the die area. Then, the CAE output are consistent as the experiment and it can to predict whether the product has a risk assessment of void.

In the conformal phased array radar, the flexible surface T/R module based on LCP substrate was studied to solve the problems such as the mismatching between components and the antenna plane and the system instability caused by the increase of plug and unplug of cable connection. The LCP laminating quality control and the chip embedding was investigated. The assembly stress on LCP multi-layer substrate was analyzed with ANSYS. The results show that optimized lamination process with auxiliary material makes the substrate flat without cavity inside. The air tightness of LCP substrate embedded with MMIC is 7.4× 10–7 Pa . m3/s. The simulation results show that the stress increases rapidly between temperature of -55 and 80 degree centigrade when the LCP substrate's bending angle is greater than 10 degrees. The conformal T/R module remains well performance with LCP substrate bending 10 degrees. The LCP substrate has a good potential in conformal phased array.

The growing diversity in the used materials in semiconductor packaging provides challenges for achieving good interconnection. Particularly the very soft substrates, such as paper and polymers, and very hard, such as silicon carbide, offer unique challenges to wire-bonding or formation of vertical interconnects. Complementary technologies are therefore needed. Here, a method to direct-write metal tracks on the top and sides of dies is demonstrated. It is based on a spark ablation aerosol printing process entirely performed at room temperature and without any applied force. Therefore, it is suitable for use on soft or temperature-sensitive substrates. The printed metal lines consist of pure Au nanoparticles, without surfactants or contaminants, and do not require any further curing, cleaning, or other processing. The process is demonstrated on Si dies and paper, but is theoretically applicable on a wide variety of substrate materials. It can provide an alternative method to create interconnects or vias on soft materials, temperature sensitive materials, irregularly shaped materials, or curved surfaces.

The development of robust artificial sensory systems that will be able to detect, memorize and respond to external stimuli is attracting a considerable amount of interest over the last years towards emulating artificial skin properties. Skin is the largest sensory system of the human body that carries out complex procedures by employing a variety of biological receptors. However, it is quite difficult to acquire stretchable artificial skin functionalities by combining the present tactile sensors. Along these lines, we report here a sensory system that has the ability to detect various strain loads with excellent sensitivity and at the same time respond and store the applied stimuli. In order to attain this goal, we used a bipolar switching memory device made on poly-ethylene naphthalate (PEN) substrate and Pt nanoparticles (NPs)-based sensor on poly-dimethylsiloxane (PDMS). The memristor operates only under strain conditions and retains the induced resistance changes even when the applied stain gauge is removed with

Currently, there is an active development of new frequency ranges (millimeter and submillimeter parts of the spectrum) due to the introduction of the 5G standard and the study of 6G networks. This leads to the fact that there is a need to develop flexible antennas for these frequency ranges. It is advisable to use graphene for these purposes, since it is possible to manufacture environmentally friendly flexible antennas on its basis. In this work, the authors aim to determine the minimum and maximum frequencies for which flexible graphene antennas can be fabricated using various graphene deposition technologies.The paper presents a comparative analysis of the possibility of using various technologies for deposition of graphene for the manufacture of antennas in the millimeter and submillimeter frequency ranges. To perform this analysis, a critical size parameter was introduced. On its basis, the minimum and maximum frequencies for which flexible graphene antennas can be fabricated are determined using the considered graphene deposition technologies.The design and characteristics of a graphene eco-friendly dipole antenna on a paper substrate, which is made using screen printing technology, are presented. An assessment of the applicability of the technology used for the manufacture of elements of the Internet of things operating in the 5G millimeter frequency range has been carried out.

This paper presents, a novel design of a Hollow Substrate Integrated Waveguide (HSIW), that is built by using both Subtractive and Additive Manufacturing technologies. Specifically, it utilizes Polymer jetting method to print an Acrylonitrile butadiene styrene (ABS) dielectric substrate and a water laser cutter system to produce smooth copper sheets as the top and bottom enclosures of the HSIW. Also, the fabrication process is utilizing mechanical through hole plating of commercially available prefabricated vias, eliminating the cost and complexity of performing vias fabrication and metallization process as in other SIW designs. The proposed waveguide covers 5G new radio frequency bands, specifically from 21 GHz to 31 GHz. It has a simulated and a measured attenuation constant of 0.636 Np/m and 1.56 Np/m respectively, for the whole operating frequency range and is among the lowest reported values to date. The proposed HSIW of this paper, can be compared with other state- of-the-art designs in terms of compactness, manufacturing cost and performance. The designed HSIW can be integrated with other planar circuits and can be used to build functional devices such as antennas or filters for 5G, robotics and IoT applications.

The method of implementing various substrate-integrated waveguide (SIW) dual-band and multiband bandpass filters (BPFs) are reviewed and summarized, which can be basically classified as three categories. A comprehensive overview of numerous technical approaches and diverse design methodologies are narratively described, including parallel-connecting method, split-type method, and dual-mode method. Future prospects for SIW dual-band and multiband BPF developments are also presented and discussed in this paper.

In this article, we present the design and realization of an electronically rewritable RF encoding particle (REP) for chipless RFID applications. This (REP) resonator geometry is integrated with two conductive bridging random access memory (CBRAM) based non-volatile RF switches, and could be electronically programmed using DC pulses to any of possible four resonant states to represent two bits of information. Emerging additive manufacturing (AM) technique based thermal transfer printing is utilized for the realization of this resonator on flexible and low cost Polyethylene terephthalate (PET) substrate. At present the size of the REP is such that five such REPs could be arranged on a standard credit card size tag. Also this REP encodes the most number of bits reported among non-volatile electronically rewritable REPs for chipless RFID applications - 2 bits, till date.

this paper proposed, a millimeter-wave microstrip patch antenna and its 1×4 array for 5G communication. The millimeter-wave microstrip patch antenna is designed on heterogeneous substrate used substrate material is RT/duroid 5880 having relative permittivity 2.2 and its substrate cut slot are filled with air this material relative permittivity is 1. the microstrip line feeding technique is used to feed this antenna. The proposed antenna resonate at 31.76GHz frequency to achieve 9.6dB gain and return loss 15.38dB. The 1×4-element antenna array is designed with dimensions 35×12 mm2 and low cost RT/duroid 5880 material and air is used as the heterogeneous substrate. The return loss of 1×4 array is 51.63dB and gain is 10.83dB at resonant frequency 28.78GHz. The antenna design and simulation is done by using CST studio suit.

As an important part of MEMS initiator, film micro-heater can meet the development needs of low-energy and miniaturization of MEMS initiator. Among them, Ni-Cr film micro-heater has attracted much attention due to its stable performance. Ni-Cr film micro-heater is composed of substrate, nickel-chromium film and pad film. According to different substrate types, it can be divided into two types of integrated structures, one is Thin-Film-on-Chip, and the other is Thin-Film-on-Header. The main difference between the two is that Thin-Film-on-Header has a higher degree of integration and is more in line with future development requirements, but the production process is complex and the consistency is poor; the production process of Thin-Film-on-Chip is simple and can be mass-produced, but the degree of integration is low. In addition, the nickel-chromium film micro-heater has the characteristics of high ignition reliability, good safety performance, and fast response. It is widely used in gas generators for automobile airbags and other devices, and can also be used in ignition devices in military products such as micro-sized ammunition.

A flexible process for fabricating thin Si-substrate chips, implemented in millimeter-wave waveguide devices, had been developed. The geometry of chip was accurately defined by a deep Si-etch process. The thickness accuracy of Si-substrate is better than 2 micrometers by performing the backside lapping and then the dry etch processes. Two thin Si-substrate millimeter wave chips with substrate thickness of 20 micrometers are presented as examples.

Spark Assisted Chemical Engraving (SACE) is an emerging micromanufacturing technology of mainly non-conductive materials like glass and ceramic. The micromachining happens due to high temperature etching in electrolytic solution by electrochemical discharges which are generated through a tool-electrode across a gas film surrounding it. The gas film shall be present so that discharges, which are the heat source, can be generated hence causing local machining of the substrate. Studies have shown that the gas film breaks and reforms every few milliseconds depending on several factors, some of which are not known or are unclearly understood. Investigation of the gas film formation, its characteristics and the factors that affect its stability could lead to enhancing the SACE machining performance. In this work an algorithm based on Artificial Neural Networks (ANN) is developed to accurately estimate the gas film formation time. The method shown is a comprehensive one that can be applied to various machining conditions of the SACE process. To our best knowledge, few attempts have been done in the field of SACE signal processing and this work is the first study where ANN is used for gas film parameters calculation.

The Meta-surface inspired Antenna Chip developed by KIT EOE Laboratory (MACKEY, Wi-Fi 2.4GHz band), is an electrically small antenna that is sufficiently robust to metal objects. However, there has been a demand to make the basic type even thinner because it is 4mm thick. Therefore, a new model, named MACKEY II (Wi-Fi 2.4 GHz band), with broadband characteristics and reduced thickness is proposed. It is adapted to create a new structure, where the antenna substrate is placed inside the AMC substrate to create a thinner dimension than the basic type. In this paper, the characteristics and feeding method of MACKEY II are presented, along with, the measurement results.

RFID tags are embedded in everyday objects providing extra functionalities and aiming to connect them to the cloud. Miniaturization of flexible RFID tags enables the integration into smaller everyday health, entertainment, food related objects, besides enhancing security and decreasing the cost. In addition, external sensor integration and readout enable new applications for the sensor tags. In this paper a miniaturized 2cm (1€ coin size) diameter antenna is combined with a flexible InGaZnO thin-film RFID chip operating at 3V and transmitting data at 7.3kHz. Moreover, the sharp threshold detection (

Transition from linear to circular economy to have a sustainable ecosystem is now prevailing in almost every sector including Flexible Hybrid Electronics. Researchers, scientists and stakeholders are putting continuous efforts in order to have sustainable solutions to support circular economy. In order to support Flexible Hybrid Electronics in a sustainable manner General Silicones with its decades of experience developed a sustainable industrial silicone-based substrate that not only possess excellent chemical and mechanical properties but also removing the drawback of low surface energy of silicone causing adhesion, bonding and printing issues, it can act as innovative sustainable platform to design printed and flexible electronics with unmet possibilities.

A design for a multifunctional structural embedded antenna was fabricated using novel materials. The system was built on top of a hybrid composite with an SU-8 polymer epoxy as the substrate and a copper patch antenna using adapted deposition methods. The antenna was designed to benefit spacecraft missions through reductions in size, risk, and overhead.

Patch antenna is one of the most common type of antenna design due to its simplicity of orientation, dimension, configuration, and ease of implementation over a vast and variety of materials: such as fabrics to printed circuit boards. This work discovers and shows how to quickly predict the efficiency of a simple patch without the need for expensive software and/or hardware using a novel equation that relates the loss tangent, dielectric constant, and substrate height to patch efficiency. This first of a kind equation is used for assessing whether the efficiency of the patch is suitable enough for use on said intended exotic material substrate that have height of 62 mils or less (which is respectfully suitable for most applications). The simple closed form equation can predict efficiency with high accuracy. Discrepancies between quick ADS electromagnetic (EM) simulations and predictions were less than 5%-7% error for various materials (with height ≤ 62 mils) at frequencies ranging from 2.5 GHz - 10 GHz., 2021 IEEE 19th International Symposium on Antenna Technology and Applied Electromagnetics (ANTEM), August 8-11, 2021, Winnipeg, MB, Canada

Substrate integrated waveguide antenna is proposed with considerable bandwidth and return loss, which is used for multi-band application is described in this paper. A general patch antenna is converted to a substrate integrated antenna by placing an array of cylindrical vias densely on the patch. The main objective of designing this antenna is to be analyzed the effect of vias when its dimensions are scaled at multi resonance operational performance of the antenna. A parametric analysis design has been proposed to obtain high bandwidth without losing its gain properties. And also, the effect of the transmitted power improvements technique has been discussed in this paper.

Microfibers are important components in the construction of fiber reinforced materials; however, precisely picking, placing and orienting microfibers remains a difficult task. This paper introduces a capillary manipulation method for handling microfibers. The micromanipulation method combines a capillary pick-and-place technique and super hydrophilic - super hydrophobic patterned surfaces. Capillary pick-and-place method was used to transfer the fibers to the substrate, and the patterned super hydrophilic – super hydrophobic surfaces was used for alignment of the microfibers. We studied influences of the key parameters including the wetting properties of the substrate, the volume of the droplet and the size of the super hydrophilic – super hydrophobic patterns on the capillary micromanipulation of microfibers. The proposed method has great potential for manufacturing complex microstructures out of microfibers.

Although superhydrophobic surfaces have been extensively studied in the past, few studies have achieved optical encryption through the manipulation of droplets combined with the surface superhydrophobic properties. We present here our work in using femtosecond laser ablation to create micro-/nano-structures on polydimethylsiloxane (PDMS) substrate surfaces, enabling them to become superhydrophobic. Directional transport tracks to steer droplet motions were designed on the processed PDMS surface utilizing a high-contrast difference in surface wettability; self-cleaning property using the droplets was also verified on the substrate surface. Moreover, using a surface with designed high-contrast regions to trap droplets, magnetic-assisted manipulation of nanoparticles enabled in-situ reversible optical imaging/encryption. Our simple method for creating high-contrast surface wettability regions holds great potential for fostering a wide range of innovative applications such as droplet-based microfluidics as well as new optical encryption devices.

Biomedical implanted devices are typically used for interacting with organs and/or for investigating various physiological signals. Hence, enhanced performance devices for clinical uses have got the attention of researchers. In this study, a multi-band implanted microstrip antenna suitable for transmitting/receiving biomedical signals in the Industrial, Scientific and Medical (ISM) frequency bands is presented. The antenna is built on a bio-compatible substrate, as titanium dioxide (TiO 2 ) with relative permittivity of 95. The ground plane is thought to be a bio-metallic implant located within a bone. The proposed antenna is compact in size, 14 × 18 × 1.6 mm3, and works in both 2.45 GHz and 5.8 GHz centered frequency bands. It is designed and optimized considering the actual biological tissues as bone, muscle, fat, and skin surroundings. The simulation results referring to a planar stratification prove that the multiband single microstrip antenna is working properly within the human body and it can be used for medical communication services.

In this paper, a new H-plane multi-horn antenna is designed for small nonmetallic unmanned aerial vehicle (UAV) application. Four H-plane horn antennas are integrated into a single square substrate using the substrate integrated waveguide (SIW) concept. In fact, they are placed concentrically and directed at the four edges of the substrate. In order to control the resonant frequency at 5.8 GHz and to obtain proper matching, the co-axial connector is placed the center of the structure. The antenna provides the quasi-omnidirectional radiation instead of the directional radiation pattern at the H-plane. The laboratory prototype of the structure is measured to validate the theoretical results. This antenna is suitable for UAV applications.

Besides bandwidth and gain actuation conflict, a microstrip antenna is easy to fabricate and install at a cheap cost. Hence makes it suitable for modern-day telecommunication and wireless device applications to introduce new antenna easy to market. However, the quest to know the best substrate material that will produce higher antenna performance at 3.6GHz prompted the consideration of different substrate materials for the design of rectangular microstrip antenna. Transmission line model (TLM) analysis was used to obtain the antenna designs' physical dimensions for the eight different substrate materials considered at a fixed height (h) of 1.6mm. The simulations were carried out in CST Microwave Studio. The evaluation results show an inverse relationship between the dielectric constant of substrate materials and the gain-as high-density polyethylene with the least dielectric constant displayed the highest gain. The FR-4 with the highest dielectric constant gives the least gain.

International audience; In this paper, a bandpass filter realized on a flexible substrate made of a cellulose-based material is presented. The operating frequency band is selected in order to address industrial, scientific and medical (ISM) applications. The bandpass filter central frequency is equal to 2.45 GHz. The filter design exploits a quasilumped microstrip structure and the circuit realized from a copper adhesive laminate is shaped by laser. The bio-sourced material is a cellulose ester. The characterization of the proposed filter demonstrates that measurement and simulation data are in a very good agreement.

Dispenser printing is a useful technique in the development of e-textile devices. However it is limited by the requirement to maintain a gap of less than 200 µm below the printer’s nozzle, making it impractical on uneven substrates. Using a laser displacement meter to record and compensate for changes in substrate height can overcome this problem. However, the binders and inks used in e-textile primer layers are typically translucent or arbitrarily pigmented. This work investigates adding specific pigments to interface paste and shows that it can improve the laser measurements’ accuracy and reduce the percentage of printing errors by 80%.

The simulation results of microstrip antennas with a substrate with various combinations of dielectric and magnetic permeability parameters are presented in the work to determine the general laws of the influence of the electrophysical parameters of the substrate on the main characteristics of the antennas. Microstrip antenna characteristics are modeled using the HFSS program.

In recent years, liquid metal materials have gradually attracted widespread attention from scholars at home and abroad due to their unique fluidity and high conductivity. Especially in the field of flexible electronics, there are endless researches on preparing liquid metal into various stretchable electronic circuits, sensors, and intelligent systems. Besides, researchers have also developed a variety of liquid metal functional materials and various liquid metal based flexible circuit preparation methods. In this research, we printed liquid metal on a stretchable substrate to prepare a stretchable sensor, which exhibits good electrical stability and can detect the movement of human body or robot joints. We believe that this kind of liquid metal stretch sensor can have broad application prospects in the fields of smart sensing, wearable electronics, and human-computer interaction.

Microlenses and microlens arrays (MLAs) are widely used in various applications, such as lab-on-a-chip, CMOS camera, and solar cells [1] . However, current fabrication methods are restricted to low fill-factor arrays, few geometry options, and flat, often rigid only, substrates. Here, we present a novel additive direct-write method, termed laser catapulting or LCP, for the rapid and customized fabrication of high fill-factor MLAs over a large variety of substrates [2] , [3] . A schematic description of LCP is shown in Fig. 1a . We used a single nanosecond laser pulse to delaminate and catapult, at user-selectable positions, either a single or a multitude of microdisks (up to 260 lenses/mm 2 ) from a donor thin film onto receiver substrate. Following thermal reflow, the printed microdisks are converted into planoconvex microlenses with excellent sphericity and high smoothness ( Fig. 1b,c ). We used as donor a positive photoresist, however, other materials can be transferred in a solid state under appropriate conditions that involve the mechanical and geometrical properties of the selected disk [4] .

Manipulating the interaction between light and matter for generating colors is becoming a hot spot of research in photonics, revolutionizing many areas, such as holographic data storage [1] , light filtering [2] , high resolution displays [3] , security [4] , and integrated opto-electronics components [5] .

This work presents the sensing part of a self-healing artificial hair sensor array that can be used for flow sensing and haptic exploration. The system consists of metallic strain gauges embedded in a flexible substrate over extrusion channels where a hair can grow. Together with the sensor array, a measurement board was developed that automatically calibrates the sensors, processes the signal and sends it to a computer. Measurements with three different surfaces prove that different materials can be recognized if these have nonidentical surfaces.

This paper presents a novel design mechanism of underwater flow sensor inspired by mechanosensitive air-retaining hairs of a backswimmer (Notonecta). The flow sensor, consists of a PDMS cantilever beam, a piezoresistor with single wall carbon nanotubes (SWCNTs) and Ag nanoparticles (AgNPs) nanocomposite on the cantilever, and a superaerophilic substrate. The SWCNTs/AgNPs nanocomposite was fabricated by a direct printing process, and a gauge factor of 150 was achieved. The air-retaining structure was created by the superaerophilic surface of the substrate and the PDMS sensing cantilever. The experimental results indicated that the sensitivity of the flow sensor with air layer was about 2.4 times higher than that of the sensor without air layer.