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Liquid transfer printing for carbon-based flexible electronics devices.

Authors:Xin Liu, Yihao Chen and Xue Feng *

In order to meet the rising needs for electronic products to integrate with various surfaces such as human body, flexible electronic technology has become an important aspect for the development of electronic industry. Flexible substrates are normally used in carbon-based devices to achieve the flexibility. After making independent different types of functional devices, a large-scale integration is extremely needed to form orderly functional system. Transfer technology provides the possibility for this integration. For instance, a PDMS stamp is normally used in the transfer process, Rogers fabricated special PDMS stamp with boundary tips which makes the printing process easier [1]. Feng uses shape memory polymer to make microstrutctures on the stamp and achieve the tranfer process with the help of temperature response [2]
However, Traditional stamp transfer involves the fracture of multi-interface[3], which leads to transfer failure due to stress concentration in high aspect ratio patterns and sharp patterns. Here we report a liquid transfer method. It makes full use of the buoyancy and surface tension of the water, leading the micro patterns to detach with the wafer automatically and be stretched by the liquid surface tension. The device remains functional after transfer printing. We transferred patterns with different Aspect ratio to confirm that there is little stress concentration caused by complicated patterns during the whole process, enabling the complex graphics to be transferred from multi-scale substrate, which is of great significance to the industrialization of flexible electronic manufacturing and the automation of transfer process.

Directly drawing flexible capacitive sensors on copying tissues

Authors:Yu-Qing Liu*, Yong-Lai Zhang#, Hong-Bo Sun†

Flexible pressure sensors that enable detection of tiny forces are promising candidates for application in intelligent devices, such as smart textiles, electronic skins, human–machine interfaces, human health monitoring and motion tracking systems, and diagnostic devices. Despite the fact that current capacitive-type pressure sensors have demonstrated high sensitivity, a large detection region and the capability to achieve non-contact detection of proximity, strategies for producing such high performance sensors still involve complex fabrication procedures and the use of polymers and costly materials. At present, a green, facile and cost-effective fabrication of high-performance flexible pressure sensors is highly desired, but it remains a challenging task. Here,we report the fabrication of paper-based capacitive pressure sensors by pencil drawing of loop- and disc-shaped graphite electrode arrays on copying tissue sheets. Graphene oxide (GO)- enhanced foam-like paper, prepared by freeze-drying of paper cellulose fibers and GO composites, was employed as a high-performance dielectric layer. The whole fabrication process is simple, green and cost-effective, and the obtained capacitive pressure sensors are highly sensitive to pressure and approaching objects, enabling detection of finger motion, touching and proximity.

Water Transfer Printing of Liquid Metal for 3D Flexible Electronics

Authors:Biao Ma, Chengtao Xu, Hong Liu*

Room temperature liquid metals (LMs) of Ga-based alloys are a kind of fascinating material possessing many excellent properties such as high conductivity, fluidity, deformability, nontoxicity and self-healing. Numerous efforts have been devoted to pattern LM on planar substrates to develop 2D flexible and stretchable electronics. However, the potential application of LM in 3D flexible and conformal electronics with enhanced component functionality is in its early stage. In this work, we report a simple and efficient method to transfer 2D LM patterns to nonplanar surfaces using the water transfer printing technique. LM was directly patterned on the water soluble film of polyvinyl alcohol (PVA) film using magnetic field, based on a novel LM patterning technique we developed previously.1 As shown in Figure 1, after dissolving the film on the water surface, the LM patterns can be easily transferred to nonplanar surfaces by dipping the 3D objects into the water, or pulling them out of the water. We also demonstrated the applications of this technique for 3D flexible touch sensor and electronics skin.

Flexible Dual-band Wireless Capsule Endoscopy Antenna Applied to Different Human Bodies

Authors:Ma Ping, Wu Xujing, Zheng Hongxing, Wang Mengjun

Antenna is absolutely necessary for the development of wireless capsule endoscopy(WCE) system, as a bridge for information transmission in vitro and in vivo. In the past few years, many WCE antennas have been proposed, which have different performance parameters and characteristics. However, the stability is relatively poor and sensitive to the surrounding environment for most antennas [1-3]. In addition, the tissue model is relatively single, which is insufficient to evaluate the stability of antenna in different environment. Therefore, it is important to research a WCE antenna which can work in different environment with good robustness.
In this work, we present a flexible dual-band WCE antenna, which contains two bands: industrial, science, medical band (ISM:433-434MHz) and wireless medical telemetry service band (WMTS:1.395-1.4GHz) for telemetry or wireless monitoring and wireless power transfer (WPT), respectively. 0.05 mm thickness polyimide as a substrate, introduces a new resonance and extends the bandwidth by loading a L-shaped branch, realized WCE antenna with ultrathin and dual-band characteristics, the geometric structure and detailed dimensions of the antenna is shown in Figure 1 and Table I. In order to evaluate the stability of the antenna, seven 3D human voxel models with different age, sex, somatotype, tissue thickness and internal environment are applied and showed in Figure 2. For saving computation time, intercepting the human voxel model abdomens, and the antenna is placed in different gastrointestinal tract organs of different abdomen models for simulating. S-parameters of the dual-band antenna in the same part of different human bodies are plotted in Figure 3. The obtained results indicate the proposed antenna is insensitive to the different human environment, has a good robustness, and suitable for various populations for transferring gastrointestinal information and power.

Flexible pressure sensor for continuous measurement of human arterial pulse wave

Authors:Keyu Meng*, Jin Yang*

Real-time heath monitoring and assessment is becoming more and more critical and indispensable, which largely contributes to the advancement of the field of wearable electronics for biomedical applications[1,2]. Pulse wave carries comprehensive information regarding human cardiovascular system, which is highly correlated to various physiological diseases related to heart. To measure the subtle changes in the pulse wave, various novel materials and nanotechnologies are applied to develop wearable sensors over the past decades, including piezoelectric materials, metal nanowires, and conductive fibers. However, the above mentioned wearable sensors are incapable of measuring the distinguishable arterial pulse wave owing to the insufficient sensitivity. Here, we reported a self- powered TENG based pressure sensor (as shown in Figure 1) for continuous measurement of human arterial pulse wave in a noninvasive real-time manner, as shown in Figure 2. Additionally, a further step was taken to develop a cost-effective, wearable, user-friendly sensor system. Via a system-level optimization, all the system components can collaboratively work together for continuous and noninvasive human health assessment and monitoring.

Dynamic mechanical properties of flexible polydimethylsiloxane subjected to impact loading

Authors:Fuxing Miao1, a *, Shanen Li1,b , Huanyu Chen2,c, Fenghua Zhou1,d

This paper presents the experimental study on the dynamic mechanical properties of the flexible polydimethylsiloxane (PDMS) species through axial compressive impact loading testing by using a split Hopkinson pressure bar (SHPB). Meanwhile, dynamic responses are investigated by finite element method simulation. The strain rate effect and dynamic responses on the flexible PDMS under impact loading are discussed in details. It can be seen that the dynamic stresses of flexible PDMS increase with the increase of impact loading and strain rate. All the dynamic compressive stress-strain curves show similar characteristics under various impact loading. The dynamic stress- strain behavior of the flexible PDMS has apparent strain rate effect. In addition, the dynamic responses occur mainly in the impact loading direction. The amplitudes of dynamic displacement, velocity and acceleration responses on the flexible PDMS increase as the strain rate increase. The displacement responses occur earlier for the bigger strain rate. The velocity responses appear a kind of platform area. The acceleration responses oscillate sharply. These preliminary findings are believed to build the foundation for future research on the impact mechanical properties of flexible electronic devices and provide design guidelines for flexible devices in engineering practice.

Silica microfiber for wearable strain and temperature sensors

Authors:J. Pan, Y. Tang, L. Zhang, L. M. Tong

Silica microfibers have been emerging as a novel sensing platform owing to their outstanding properties including low waveguiding losses, tight optical confinement, strong evanescent fields, and small bending radius [1]. When a silica microfiber is embedded in a thin layer of PDMS film, the PDMS film not only provide natural protection of the microfiber, but also serve as an effective external stimuli transducer due to its low Young’s modulus, high Poisson’s ratio coefficient and large thermooptic coefficient [2]. Enabled by the transition from guided modes into radiation modes of the waveguiding microfibers upon external stimuli, one can detect human physiological signals in real time by attaching a microfiber sensor to skin or cloth. Herein, we demonstrate highly sensitive wearable microfiber sensors for monitoring respiratory rate and body temperature.

Mechano Regulated Metal Organic Framework Nanofilm for Ultrasensitive and Anti Jamming Strain Sensing

Authors: Liang Pan1,2,3, Wenxiong Shi2, Gang Liu1,3, Wan Ru Leow2, Yaqing Liu2, Meng Xiao2, Shuzhou Li2, Xiaodong Chen*2 and Run-Wei Li*1,3

Effectively and purposefully modulating the charge transport process, and successfully designing a functional electrical device always are the crucial issue for metal-organic frameworks (MOFs). Herein, we report a strategy for realizing tunable conductivity in MOFs I2@CuTCA (H3TCA = tricarboxytriphenyl amine) through shrinkage and expansion of frameworks upon the external applied strain (Figure 1). A molecular dynamics simulation and experimental observations suggest the performance are strongly regulated by the related movement of guest molecular I2 in the nanochannels through strain-induced shrinkage and expansion of the frameworks in I2@CuTCA. More importantly, we have developed a smart and low-cost kneecap based on the experimental phenomenon, which can precisely count the step of our sporting by the large motion of knee joint (Figure 2). Through the period and amplitude, we could estimate how much energy we have burned during running, walking and riding which is helpful for the bodybuilding and lost weight. The discovery of strain-induced resistive switching behavior in MOFS offers great potential as sensors in future wearable electronic devices [1-2].

Buckling guided assembly of flexible 3D structures and electronics based on engineered dielectric elastomer platform

Authors:Wenbo Pang#, Xu Cheng#, Wen Huang†, Xiaogang Guo#, Lei Sang‡, Haojie Zhao‡, Yihui Zhang#,*

Recently developed approaches of mechanically-guided assembly allows the deterministic formation of complex three-dimensional (3D) mesostructures in a broad set of functional materials, over length scales from nanometers to centimeters. Previous studies mostly exploited homogenous elastomer substrates, in which the deformations are uniform and controlled mechanically, thus limiting the capability to reshape into different 3D configurations. This work introduces a set of design concepts using dielectric elastomer actuators (DEA) as the 3D assembly platforms, which could offer independently controlled, sequential, local deformations of the substrates. Quantitative experiments and numerical simulations illustrate the capabilities of the dielectric elastomer (DE) platform in achieving complex deformation characteristics, e.g., tunable deformable field via multiple individually addressable electordes, isolation of strain field and high loading speed. Demonstrations include nearly 30 examples, including morphable 3D structures, froglike structure, eyeglass-like structure, starfish-like structure, and 3D structures that resemble Beijing National Sports Center. A tunable inductive-capacitive (LC) radio-frequency (RF) circuit consisting of a morphable 3D capacitor serves as an application example.

A novel approach to measure the convective heat transfer coefficient based on pulse heating

Authors:Zujun Peng1, Ying Chen1, Xue Feng*2, 3

Convective heat transfer coefficient (CHTC) is a significant quantity that is needed for the thermal system design. This paper proposes a novel approach to estimate the CHTC through pulse and isothermal heating. The ideal isothermal heating process has been realized through multi-layer structure design, which has been fully validated by the finite-element model and thermal imaging experiment, even for specimens with low thermal conductivity. Moreover, based on the simulation model, we analyzed the thermal response law of multilayer structure and obtained the optimization design criteria. During pulse heating, convective heat transfer coefficient can be simultaneously estimated using the proposed method, and the relative numerical errors will be less than 5.5% with virtual temperature data. Finally, we prepared the flexible CHTC sensor, and obtain consistent results with a coefficient of variation no more than 0.02 through different data, which further verifies the effectiveness of the method.

Human Skin-Inspired Electronic Sensor Skin with Electromagnetic Interference Protection

Authors:Junhong Pu, Mingbo Yang, Wei Yang*

Increasingly serious electromagnetic radiation pollution puts higher demands on wearable devices. Sensor skin capable of shielding electromagnetic radiation can provide extra protection in emerging fields such as electronic skins, robotics, and artificial intelligence, but combining the sensation and electromagnetic shielding performance together remains a great challenge. Here, inspired by the structure and functions of the human skin, a multifunctional electronic skin (M- E-skin) with both tactile sensing and electromagnetic radiation shielding functions is proposed. The tactile sensing of human skin is mimicked with irregular dermislike rough surfaces, and the electromagnetic shielding performance not available on natural skin is introduced by mimicking the ultraviolet driving radiation absorption of melanin in epidermis. The M- E-skin shows superior sensitivity (9.8×104 kPa−1 for the pressure range 0−0.2 kPa and 3.5×103 kPa−1 within 0.2−20 kPa), broad operating range (0−20 kPa), fast response and relaxation times (<62.5 ms), great pressuring- relaxing stability (10 kPa, 1000 cycles), low operating voltage (0.1 V), low power consumption (1.5 nW), and low detection limit (5 Pa). Besides, a broad range of electromagnetic wave (0.5−7.5 GHz) is shielded more than 99.66% by the ME-skin. This work holds great potential to enlarge the application scope of current electronic skins.

Prepare of arrays arranged flexible EMG electrodes and identification of muscle fatigue

Authors:Yizhou Qi*, Liushun Ye*, Ying Chen*

Recognition and analysis of electromyography (EMG) signals have been applied in the detection of neuromuscular diseases[1, 2, 5]. However, there is still limitation of measuring the EMG signals in measured location, connecting and accuracy by using the traditional electrodes. In this work, micro-fabrication technology[3, 4, 6, 7] will be used to design and manufacture flexible EMG electrode devices with electrode arrays arranged on its surface. A signal acquisition system based on the flexible EMG electrodes will also be established to realize the convenient, real-time, multi-part and wearable acquisition of spatial distribution of EMG signals. Mechanical characterization experiments, electrical test experiments and numerical calculation methods will be carried out to optimize the electrode structure, thus improve the mechanical properties and signal acquisition performance of the electrodes. Depending on the flexible EMG electrodes, acquisition methods based on the spatial EMG signal distribution will be studied. Methods of feature signals extraction and pattern recognition analysis will be developed to improve the accuracy of identification of muscle fatigue. This work aims to integrate a set of EMG signal acquisition system based on the arrays arranged flexible EMG electrodes, and develop the analysis and identification methods for identification of muscle fatigue as well as other muscle diseases, which will be of great significance for promoting the development of wearable intelligent medicine systems.

Strain-Sensitive and -Insensitive Stretchable RF Patch Antennas

Authors:Lei Sang#, Kehan Dai#, Wen Huang*

As the critical component in the wireless communication systems, RF patch antennas fabricated on elastomer materials have attracted widespread attention and have been developing rapidly [1,2]. In general, stretchable RF antennas could be used in two primary cases : 1. In the first case, the electrical characteristics of a stretchable antenna are sensitive to the stretching of the soft substrate, so that a characteristic signal is generated in real-time for the monitoring of soft substrates morphological changes; 2. In the second case, the electrical performance of a stretchable antenna is insensitive to the deformation of the carrier, so that the performance of the wireless communication system is not significantly impacted under mechanical strain. Therefore, according to the different requirements of the above application scenarios, it is important to select the appropriate antenna type, and to alter the fabrication processes for the antenna in order to fit the elastic substrate and conductive material properties accordingly. The performance of the antenna will then become related not only to the frequency domain, but also to the strain of the substrate [3]. A general, simple method for the design, fabrication and application of stretchable RF patch antennas is highly desired.

Fabrication of the Ultrasensitive Flexible Capacitive Pressure Sensing Coating

Authors:Tianyu Shao † , Yuhan Zhang †, Peng Zheng †, Zhuo Li†,*

The Internet of Things is recognized as one of the most important areas of future technology and has received wide attention. As an important component receiving information from the outside world for the Internet of Things, the development of wireless sensor networks has always been an important factor restricting the popularity of the Internet of Things. Sensors based on different working mechanisms including piezoresistive, capacitive, piezoelectric, and triboelectric ones have been fabricated. Among them, capacitive pressure sensors have been widely used because of their low energy consumption, simple structure, and high reliability.
At present, methods to improve the sensitivity of the capacitive flexible pressure sensor mainly focus on preparing the microstructure on the surface or inside of the dielectric layer to increase the change of thickness when pressed, or increasing the facing area between the electrodes. These methods have certain limitations: the high sensitivity can only be maintained in a small pressure range, and it is difficult to fit well with the curved surface. In addition, the nonlinear response of those capacitive pressure sensors increase the difficulty in data interpretation. In this work, we innovatively propose two methods for preparing the dielectric layer of capacitive pressure sensor, and study its performance furthermore.

High-Performance Flexible Photodetector Arrays Based on All-inorganic Perovskite Quantum Dots

Authors:K. Shen*, H. Xu*, X. Li*, M. Wang#, K-L. Choy#, H. Liu*, and J. Wu*†

With rapid development of flexible electronics (FE), the demands for portable, wearable and arrayed devices are ever increasing. Promising for large-scale integrated FE, perovskites have recently attracted numerous attentions due to their excellent optoelectronic properties, low cost and compatibility with flexible substrates.[1] Here, 32 × 24 vertical-stacked flexible and high- performance photodetector arrays are demonstrated, based on the optimized all-inorganic perovskite nanocrystals, as shown in Figure 1. The blending of CsBr/KBr precursor is used to reduce surface states as well as facilitate charge transport, which resulted in the improved optical properties and film formation. By precisely controlling the ratio of CsBr/KBr mixture, the perovskite-based flexible photodetector arrays exhibit excellent photoresponse features, especially at zero biased voltage, including high photoresponsivity of 141 mA/W, remarkable specific detectivity of 1.25 × 1012 Jones and large on/off ratio of 8.1 × 104. Moreover, such photodetector arrays sustain the electrical stability under large banding angles up to 170∘ and reproducible flexibility after hundreds of bending cycles, indicating a great potential for optical communication, digital display and artificial electronic skin applications.

High-Performance, Flexible, and Transparent Supercapacitor Based on Co(OH)2 Nanosheets/Ag Nanowires Hybrid Network

Authors:Hongwei Sheng, Wei Lan*, Erqing Xie

A future trend in wearable electronics will be the shift toward optically transparent devices. High-performance flexible transparent electrodes are the prerequisite of building flexible transparent supercapacitors (FTSCs), as it requires active materials to be sufficiently transparent without compromising energy storage. In this work, we manipulate the morphology of the active materials and the junctions on the current collector to achieve optimum electronic/ionic transport kinetics. Two-dimensional Co(OH)2 nanosheets with single or two layers were vertically aligned onto a modified Ag nanowires (AgNWs) network using an electrochemical deposition−UV irradiation approach. The metallic AgNWs network endows high transparency while minimizing the contact resistance with the pseudocapacitive Co(OH)2 nanosheets. The Co(OH)2 nanosheets self-assembled into a three-dimensional array, which is beneficial for the fast ion movements. Collectively, these findings provide feasible solutions of transition hydroxides as high-performance electrode materials in FTSCs.

Physically Transient Resistive Memory by Solution-processed Magnesium Oxide on Flexible Substrate

Authors:Fang Song*, Jing Sun*, Hong Wang*, Xiaohua. Ma#, Yue Hao#

Transient RRAM devices are very attractive in information security applications and eco- friendly electronics owing to the triggered failure and degradation characteristics by external stimulus such as bio-fluids and water. With the development of flexible electronics, it is innovative to realize the conformal integration of transient RRAM devices with flexible substrates for practical applications. The biomaterial-based transient RRAM devices showed good flexibility while suffered poor electrical performance. The inorganic based transient RRAM devices always need high vacuum process which is not compatible with low coat technology for flexible electronics. As a consequence, the solution process is highly desirable in flexible applications owing to its unique advantages, such as simplicity, low cost fabrication processes, and the potential for large-area fabrication. Therefore, the development of high- performance solution processed transient memory devices has great potential in low-cost flexible memory systems, wearable devices and bio-integrated electronics.

Self-assembling of Nanomaterials via Droplet Manipulation for Flexible Optoelectronics Device

Authors:Meng Su*

Based on the innovation of nanomaterials assembly, droplet manipulation and surface patterning, we accomplished the droplet manipulation strategy via Green Printing technology, which is demonstrated for rapidly patterning materials over a broad range of compositions and accurately achieving the correct position at the micro- and nanoscale. The basic units (dot, line, plane and stereo structures) via the droplet manipulation can be precisely controlled, which contribute the remarkable applications on sensitive electronical skin, flexible display, transparent touch screen, multi-layer circuits and ultra-integrated complex circuits. Nanoparticle-based curves are assembled through pillar-patterned silicon template-induced printing, and integrated as flexible sensors to perform complex recognition of human facial expression.[1] 0D microdots are connected by 1D microwires through regulating the Rayleigh-Taylor instability of materials solution or suspension, which display bright dichromatic photoluminescence.[2] The 3D architectures achieved by two different quantum dots show non-interfering optical properties with feature resolution below 3 μm.[3] The mirofiber-knitted conductive cross-weave patterns are achieved for fabricating multiresolution flexible electronics to monitor whole-body physical kineses.[4] The optimal interconnect leads to a 65.9 percent decrease in the electromagnetic interference.[5]

Fabrication of enhanced silver nanowire films via self-assembled gold nanoparticles without post-treatment

Authors:Qi Su, Qiang Zou*

Transparent Silver nanowire (AgNW) electrodes have been widely explored in many applications as a promising alternative to relatively expensive indium tin oxide (ITO). For these applications, high contact resistance at the junctions of AgNWs is a main problem to be solved. In this paper, gold nanoparticles (AuNPs)-self-assembled method has been demonstrated to improve the optoelectronic performance of AgNW films. The sheet resistance of this novel AgNW film is measured as low as 13.2 Ω/sq, and the transmittance is high to 86.1 %. Self- assembled AuNPs can enrich the percolation paths between AgNWs with negligible loss of optical properties, thereby realizing the excellent optoelectronic performance of AgNW films. Moreover, no extra post-treatment procedures are needed for the fabrication process. All these advantages indicate this method has great potentials for achieving high performance transparent electrodes in emerging optoelectronic devices.
Parts of AgNW surface are attached with AuNPs after adding AuNPs solution into pristine AgNW solution. The schematic morphologies of both pristine AgNW and AuNPs-decorated AgNW solution are shown in Fig. 1a,b, respectively. The SEM image of pristine AgNW are shown in Fig. 1e,f, indicating a smooth surface. However, the AuNPs-decorated AgNWs show a rough surface in Fig. 1g,h. To verify that the AgNWs are decorated with AuNPs, Energy Dispersive X-Ray (EDX) mappings of Fig. 1g are illustrated in Figs. 1i,j. After each rod-coating process, the thin liquid (20 μm) films of ethanol, which is covering entire substrate, quickly break up into a large amount of small slices. These small slices of ethanol are more likely aggregate at nanowire junctions and nanogaps that acting as a certain kind of capillaries [1], as illustrated in Fig. 1c. Parts of the AuNPs decorated on the nanowire surface are gradually released into ethanol, while the moving range of AuNPs depends on the size of ethanol droplet. Most of the AuNPs in the ethanol droplet tend to move towards the center of droplet due to the surface tension gradient and this phenomenon is described as Marangoni effect [9]. After ethanol evaporation process completing, most of the AuNPs in the droplet are absorbed at junction and nanogaps, as illustrated in Fig. 1d and corresponding SEM image (Fig. 1k). The further evidence that AuNPs are self-assembled at the junctions and nanogaps are shown in Fig. 1l and its broader view Fig. S1. The two lines of AuNPs are parallel to each other and the blank space between them is the trace of AgNW, which is shifted to other place due to mechanical force in rod-coating process. It can be seen that most of AuNPs are aggregated in the region of two lines and few AuNPs are absorbed on the other substrate, indicating that AuNPs are self- assembled by capillary force.

Biodegradable and Flexible Threshold Switching Device for Secure Storage Application

Authors:Jing Sun *, Zhan Wang*, Fang Song*, Hong Wang*, Xiaohua Ma†

Memristive devices based on transient materials are promising candidates for next-generation secure memory applications due to their ideal storage capability, desirable scalability and 3D integrated potential, which are capable of physically vanishing at prescribed times after achieving their target functions [1]. However, the sneak path currents in neighboring device have become a considerable barrier to achieve stable memristor arrays with high integration density [2]. To deal with such a problem, it is essential to develop a physically transient access device to switch the memory device on and off effectively. We introduce here a biodegradable threshold switching device with a cross-point structure of W/Ag/MgO/Ag/W stack, which exhibits high selectivity of 107, steep turn-on slope of < 8mV/dec and fast ON/OFF switch speed of 50/25 ns. To examine the dissolution characteristic of the threshold switching device for security applications, we performed transient experiment by soaking the device arrays in deionized water at room temperature. The selectivity of the transient device began to degenerate after soaking in deionized water for 4 min and triggered failure was finally completed after 8 min dissolution. Importantly, the water-assisted transfer printing technique was employed to transfer the threshold switching device arrays onto flexible polydimethylsiloxane (PDMS) substrate and water-soluble poly (vinyl alcohol) (PVA) substrate respectively, which depended on the infiltration of water between the hydrophilic Ni layer and SiO2 layer. It was found that none of any noticeable degradation could be observed under a bending radius of 2 mm and the resulting system on PVA substrate finally disintegrated in deionized water within 30 min. In addition, a resistive switching device consisting of Mg/MgO/W stack was integrated with the threshold switching device vertically to build a one selector-one resistive swithing memory (1S1R) structure. It was obvious that the threshold switching device effectively controlled the magnitude of current of the 1S1R cell in the OFF state. To further confirm the feasibility of the 1S1R structure, the maximum array size of the system was calculated for an N × N crossbar array with the worst case read scheme. And the maximum array size of 107 Gb of the 1S1R cell could be guaranteed. This dissolvable threshold switching device could potentially be applied in neuromorphic engineering, wearable electronics and implantable electronics.

Current page 4, Total 7 pages, 134 records
  • Abstract submission
    May 1, 2019
    Extended to May 10, 2019
  • Notification of acceptance
    May 10, 2019
    Extended to May 15, 2019
  • Early registration
    May 20, 2019
  • Registration payment
    June 20, 2019
    Extended to June 30, 2019
  • Exhibition payment
    June 30, 2019
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Institute of Flexible Electronics Technology of Tsinghua, Zhejiang
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Shaoxu He   Email: heshaoxu@gfeit.org

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