Multifunctional Electronic System Research Articles

Future Thread: Printing Electronics on Fibers.

This article introduces a methodology to increase the integration density of functional electronic features on fibers/threads/wires through additive deposition of functional materials via printed electronics. It opens the possibility to create a multifunctional intelligent system on a single fiber/thread/wire while combining the advantages of existing approaches, i.e., the scalability of coating techniques and the microfeatures of semiconductor-based fabrication. By directly printing on threads (of diameters ranging from 90 to 1000 μm), micropatterned electronic devices and multifunctional electronic systems could be formed. Contact and noncontact printing methods were utilized to create various shapes from serpentines and meanders to planar coils and interdigitated electrodes, as well as complex multilayer structures for thermal and light actuators, humidity, and temperature sensors. We demonstrate the practicality of the method by integrating a multifunctional thread into a FFP mask for breath monitoring. Printing technologies provide virtually unrestricted choices for the types of threads, materials, and devices used. They are scalable via roll-to-roll processes and offer a resource-efficient way to democratize electronics across textile products.

Functional magnetic alginate/gelatin sponge-based flexible sensor with multi-mode response and discrimination detection properties for human motion monitoring

The functional flexible sensors that can simultaneously detect multiple external excitations have exhibited great potential in the human-machine interaction and wearable electronics. However, it is still a primary challenge to develop a multi-mode sensor that can achieve sensitivity equilibrium towards different stimuli, and effectively recognize external stimulus while in a facile and cost-effective material and methodology. This study presented a functional flexible sensor based on natural polymer sodium alginate and gelatin sponge electrode which could detect both external mechanical and magnetic stimuli with superiorities of outstanding sensing capability and stability. With the optimal multilayered structure, it possessed high magnetic responsive sensitivity of 0.45 T−1, excellent stability and recoverability. Its electrical property variations also displayed high sensitivity and durability under cyclic stretching, bending and compressing stimuli for 1000 cycles. More importantly, the sensor could not only respond to magnetic field and compression stimuli with contrary electrical responses, but also recognize the respective input signals to decouple different stimuli in real time. Furthermore, it was developed as electronic skins and smart sensor arrays for human physiological signals and mechanical-magnetic detection. Based on excellent multifunctional response characteristics, the sensor showed significant potential in next-generation intelligent multifunctional electronic system and artificial intelligence.

Highly Permeable and Ultrastretchable Liquid Metal Micromesh for Skin-Attachable Electronics

Stretchable electronics represents an emerging technology for next-generation smart wearables toward intimate integration with the human body. In contrast with functional devices constructed over elastomer films with limited moisture permeability, a soft electronic textile may represent the ideal skin-attachable platform to achieve long-term wearing comfort. The advancements in this active area largely hinge on a new generation of permeable conductor. Despite its intrinsic mechanical deformability, gallium-based liquid metal typically represents an impenetrable barrier for gases and liquids. In this study, we introduce a liquid metal micromesh on electrospun microfiber textile as a highly permeable and ultrastretchable conductor. The fabrication process involves dropcasting liquid metal onto an elastomeric microfiber textile followed by high-speed rotation to remove the excessive coating. The liquid metal micromesh exhibits low sheet resistance (0.38 Ω/sq), ultrahigh stretchability (>1000% strain), and mechanical durability. The porous morphology enables a high steam permeability and perception of comfort comparable to those of standard textiles. The conformal interface with the skin gives rise to low contact impedance better than that of state-of-the-art Ag/AgCl gel electrodes. The successful implementation of the liquid micromesh conductor in a multifunctional electronic system demonstrates its practical suitability for a broad range of applications in stretchable and wearable electronics.

Electronic system for documentation of the grape gene pool for assessing the ecological potential of varieties and their use in breeding

The need to create a multifunctional electronic system for documentation of the grape gene pool, focused on the characteristics of its ecological potential, has been updated. The step-by-step development of the system architecture of the grape gene pool documentation program, including the program interface, is presented. As the characteristics that most fully describe the economically valuable characteristics of grape varieties, 85 indicators were selected, and they were grouped according to functional characteristics into 9 groups. The logical structure was created and the physical design of the database was carried out. An electronic information Database has been formed, the development of which is focused on the characteristics of the obtained potential of genotypes carrying breeding significant traits, their classification, certification and areas of use. In the process of research, the screening of the grape gene pool by environmental parameters was carried out, which are based on analytical methods grouped that make it possible to obtain a complex of physiological and biochemical indicators characterizing the resistance of plants to extreme stress factors of the environment. To implement the task of varieties selection according to specified criterions, three algorithms are implemented depending on the type and user requirements for the selected varieties. In view of the environment stress full increasing and the need to focus on the ecological characteristics of varieties, the algorithms for their assessment have been developed with a focus on weather and climatic peculiarity. In order to rank variety forms according to the degree of resistance to dehydration and extreme low and high temperatures, a scale of tester varieties (standards) from low to highly resistant has been developed. The original own scale is proposed to assess every type of resistance.

Paper-Cut Flexible Multifunctional Electronics Using MoS2 Nanosheet.

Art and science represent human creativity and rational thinking, respectively. When the two seemingly opposite fields are intertwined, there is always a life-changing spark. In particular, the integration of ancient traditional Chinese art into the latest electronic devices is always been an unexcavated topic. Fabricating two-dimensional material with a tensile strain less than 3% with an ultimate global stretch has been an important problem that plagues the current flexible electronics field. The current research is limited to material in small scale, and it is always necessary to develop and extend large-sized flexible electronic systems. Here, inspired by the traditional Chinese paper-cut structure, we present a highly deformable multifunctional electronic system based on the MoS2 nanosheet. In this work, we first demonstrate how the traditional paper-cut structure can open the view of flexible electronics. In order to obtain a large area of MoS2 with excellent performance, we use a metal-assisted exfoliation method to transfer MoS2, followed by fabricating a field effect transistor to characterize its excellent electrical properties. Two photodetectors and a temperature sensor are produced with good performance. The mechanical simulation proves that the structure has more advantages in stretchability than other typical paper-cut structures. From the experimental and mechanical point of view, it is proved that the device can work stably under high deformation. We finally show that the device has broad application prospects in highly deformed organs, tissues, and joints. These findings set a good example of traditional Chinese culture to guide innovation in the field of electronic devices.

Reduction of Leakage Current Along Polyimide Layers in Wafer Level Packaging

Wafer level packaging (WLP) has become the backbone technology for chip-scale packaging and 3D integration used in compact, light-weight, and multifunctional electronic systems. Metal redistribution lines (RDL) and insulating polymer layers are the core constituents of WLP and the lateral leakage current between close-spaced RDLs have been a major concern for the electrical reliability in a dense package. In this article, it is demonstrated that Ar plasma related polyimide (PI) damage is the main cause of leakage current rather than metal residue from the RDL wet etch on the polymer surface. Through the optimization of the etch conditions after the PI descumming process by lowering RF power and raising ICP power for plasma, the leakage current of 1.6 μA is reduced to less than 5 nA. Furthermore, a model is proposed to explain the current conduction along the damaged PI layers. The results will be applicable to the fabrication of electronic devices and circuits on plastic substrate utilizing plasma-assisted processes.

Single-Layer Graphene-Based Transparent and Flexible Multifunctional Electronics for Self-Charging Power and Touch-Sensing Systems.

Applications in the field of portable and wearable electronics are becoming multifunctional, and the achievement of transparent electronics extensively expands the applications into devices such as wearable flexible displays or skin-attachable mobile computers. Moreover, the self-charging power system (SCPS) is the core technique for realizing portable and wearable electronics. Here, we propose a transparent and flexible multifunctional electronic system in which both an all-in-one SCPS and a touch sensor are combined. A single-layer graphene (SLG) film was adapted as an electrode for the supercapacitor, touch sensor, and a triboelectric nanogenerator (TENG), thus making an electronic system that is ultrathin, lightweight, transparent, and flexible. Capacitive-type transparent and flexible electronic devices can be simultaneously used as an electrochemical double-layer capacitance-based supercapacitor and as a sensitive, fast-responding touch sensor in a single-device architecture by inserting a separator of polyvinyl alcohol-lithium chloride-soaked polyacrylonitrile electrospun mat on polyethylene naphthalate between two symmetric SLG film electrodes. Furthermore, a transparent all-in-one SCPS was fabricated by laminating a TENG device with a supercapacitor, and high-performance electric power generation/storage capability is demonstrated.

Schottky junction based self-powered photodetectors and their performance modulation by multifield coupling effect

Aiming to overcome the limitation of manufacturing technology at atomic scale, “More than Moore’s law” has been recognized as a promising route to develop the next generation micro-nano electronics in the recent years. These new devices have been designed to minimize the non-digital units to nanoscale and to integrate these units into a multifunctional electronic system. The non-digital units usually contain the power source, sensing units, charge transfer devices, switches, amplifier and etc.

PCB Near-Field Transient Emission Time-Domain Model

This study is aimed at the time-domain (TD) electromagnetic compatibility (EMC) modeling of a planar near-field (NF) emission. The radiated EMC model is built, consisting of elementary dipole array, capable of accurate reproduction of NFs emitted by electronic circuits with transient excitations of nanoseconds duration. The details of the modeling approach are explained. The determination method of dipole parameters from the given time-dependent scanned 3-D electromagnetic (EM) field is developed. The proposed TD model was validated first with ideal sources excited by electrostatic discharge standard surge currents. Then, it was validated with the experimental scanned magnetic NF radiated by a microstrip circuit excited by a pulse RF signal. The magnetic field predictions confirmed the modeling procedure correctness. Modeling errors in reproducing the scanned transient 3-D EM field were better than 0.1%. Errors in NF to NF transformation of the transient EM field were in the range of 2%. The suggested model is particularly useful for the EMC NF emission investigation of modern multifunctional electronic systems with a mixture of analogue and digital blocks generating transient and impulse disturbances.

Thermally Controlled, Patterned Graphene Transfer Printing for Transparent and Wearable Electronic/Optoelectronic System

Graphene has been highlighted as a platform material in transparent electronics and optoelectronics, including flexible and stretchable ones, due to its unique properties such as optical transparency, mechanical softness, ultrathin thickness, and high carrier mobility. Despite huge research efforts for graphene‐based electronic/optoelectronic devices, there are remaining challenges in terms of their seamless integration, such as the high‐quality contact formation, precise alignment of micrometer‐scale patterns, and control of interfacial‐adhesion/local‐resistance. Here, a thermally controlled transfer printing technique that allows multiple patterned‐graphene transfers at desired locations is presented. Using the thermal‐expansion mismatch between the viscoelastic sacrificial layer and the elastic stamp, a “heating and cooling” process precisely positions patterned graphene layers on various substrates, including graphene prepatterns, hydrophilic surfaces, and superhydrophobic surfaces, with high transfer yields. A detailed theoretical analysis of underlying physics/mechanics of this approach is also described. The proposed transfer printing successfully integrates graphene‐based stretchable sensors, actuators, light‐emitting diodes, and other electronics in one platform, paving the way toward transparent and wearable multifunctional electronic systems.

Advanced TSV Filling Technology for 3-Dimensional Electronic Packaging

The development of 3D integration is necessarily required for high speed, high density, small size, and multi-functional electronic devices. Through silicon via (TSV) technology has been rapidly developed to fulfill the demand of the next generation of multifunctional electronic systems as one of the most alternative applications for 3D packaging. In this study, low cost and high speed molten solder-filling of TSV and bonding process by using micro bump was investigated. Micro bumps were formed with two step, Cu pillar bump and Sn-Ag cap bump by using electroplating. The size of micro-bumps was 10 and 20um and the precise content of the bump was developed with good planarity by adding reflow process. Additionally, the SiC nanoparticle composite solder was fabricated for low CTE filling material. From the results, it is possible that the CTE of composite solder added 1.0wt% SiC nanoparticles had decreased until 15.0ppm/°C. Comparing CTE of pure Sn, which was about 24.0ppm/°C, it was very low CTE and lower then CTE of Cu (16.5ppm/°C). Even if the electrical resistance of nanopowder composite solder is increased, the increasing rate is very slow until 1.0 wt%. However, the resistance changing rate is rapidly increased over the 1.0wt%. From the result, it is expected that nanopowder composite solder can contribute high reliability of molten solder filling TSV.

Measurement of safety factor using Hall probes on CASTOR tokamak

Hall sensors offer an attractive true non-inductive method of magnetic field measurements for fusion devices. However, there is only limited experience in using of these sensors in such demanding environment (high heat loads, radiation, and electromagnetic noise). Recently, a combined magnetic probe was developed for CASTOR tokamak, which contains 3 Hall sensors and 3 coils arranged to measure all three components of magnetic field approximately in a single point of space. The probe is compatible with in-vessel use well in confinement region of CASTOR. It is fully controlled by multi-functional electronic system that drives the Hall probes, amplifies their output signals, performs the A/D conversion and stores the measured data on PC. The bandwidth of the system is up to 200 kHz. Design of the system and its implementation on CASTOR is reviewed. Results obtained using this diagnostic on CASTOR tokamak is presented. Radial profile of the poloidal magnetic field is used to deduce radial profile of safety factor.

Biomimetic self-assembly of a functional asymmetrical electronic device.

This paper introduces a biomimetic strategy for the fabrication of asymmetrical, three-dimensional electronic devices modeled on the folding of a chain of polypeptide structural motifs into a globular protein. Millimeter-size polyhedra-patterned with logic devices, wires, and solder dots-were connected in a linear string by using flexible wire. On self-assembly, the string folded spontaneously into two domains: one functioned as a ring oscillator, and the other one as a shift register. This example demonstrates that biomimetic principles of design and self-organization can be applied to generate multifunctional electronic systems of complex, three-dimensional architecture.

Lightning protection for microprocessor-based electronic systems

The issues of lightning threats, suppressor components, and guidelines for selection and placement of protectors are addressed. Case histories are also reviewed. It is noted that current complex, multifunctional electronic systems are composed mainly of sophisticated microcircuits that are extremely vulnerable to lightning-caused transient voltage spikes. Properly selected and installed surge protection devices have a long history of proven capability in virtually eliminating costly downtime and repairs. Telecommunication station protectors usually allow voltage spikes of 500 V or more to pass on through to downstream equipment. They are designed for protection of personnel and also equipment that the telephone company connects to the system. Modems and other interfaces may not have built-in hardness to sustain 500 V spikes or adequately protect against temporary malfunctions. Supplemental protective devices for modems and other signal lines can boost transient immunity by orders of magnitude with a relatively low investment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>