Interdigitated Electrodes Research Articles

Investigation into the influence of interdigital parameters on electrochemical performance for in-plane supercapacitors via mathematical modeling and conformal mapping techniques

Herein, we propose a mathematical model and corresponding analytical transformation approach based on the conformal mapping technique and equivalent circuit conversion method to investigate the influence of interdigital parameters such as electrode length (Le), width (We), and spacing (De) on the electrochemical performance of in-plane supercapacitors (SCs) fabricated via CO2 laser processing on polyimide film and encapsulation with PVA/H3PO4 gel electrolyte. We conclude from the experiments that the small gap ensures a compact structure, a high electrode utilization rate, and a short anion/cation transport channel, while the large electrode area generates a sufficient electrostatic double-layer effect to improve areal capacitance. Furthermore, interdigital length and width are particularly sensitive to capacitve performance, implying that electrode area plays a critical role. Eventually, the optimal electrode parameters are 10 mm (Le), 1.5 mm (We), and 0.35 mm (De), delivering high areal capacitance (2.43 mF/cm2), relatively low resistance (≈46 Ω) and excellent areal energy density (225 μWh/cm2) and power density (3.65 mW/cm2). Because the experimental values are compatible with the simulation curves and the different percentages between them are controlled within 13 %, the mathematical model has theoretical significance for the design of interdigital electrodes.

Facile and Controllable Ultrasonic Nebulization Method for Fabricating Ti3C2Tx‐Based Strain Sensor and Monitoring of Human Motion and Sound Wave

AbstractFlexible and wearable electronic devices hold great potential in electronic skins, health monitoring systems and soft robotics. Among them, flexible strain sensors with high performance are key components for wearable health monitoring devices. However, the facile and controllable preparation of highly sensitive sensors still faces significant challenges. By virtue of excellent conductivity of 2D transition metal carbids (MXenes), this work reports a facile and low‐cost fabrication strategy for large‐scale production of strain sensors. The sensitive layer is deposited on flexible interdigital electrodes by ultrasonic nebulization of Ti3C2Tx nanosheets. By controlling the nebulization time, different thicknesses of Ti3C2Tx films has a great influence on the performance of strain sensors. The Ti3C2Tx‐based strain sensor exhibits good sensing performances such as high GF (19.1) in the low strain range (≈0.25%–1.14%), short response time (0.7 s), and stable durability (over 1000 cycles). In practice, the potential applications of the strain sensor in sound frequency detection, human physiological signal monitoring and facial expression recognition are demonstrated. Finally, this work integrates the strain sensor with a miniaturized analyzer to assemble a wearable motion monitoring device for mobile healthcare. This study provides a facile strategy for fabricating flexible strain sensors in the field of wearable electronics.

Three Different Rapidly Prototyped Polymeric Substrates With Interdigitated Electrodes for Escherichia coli Sensing: A Comparative Study.

This work delves upon the development of different types of miniaturized and 3D printed devices having interdigitated electrodes (IDEs) for the detection of Escherichia coli (E. coli) bacteria. The IDEs were fabricated using different approaches including laser-induced graphene (LIG) on polyamide, direct laser writing on glass, and polymeric 3D printing technique, and their suitability for bacteria detection has been compared. The electrochemical impedance spectroscopy (EIS) technique was employed to detect the E. coli bacteria in the prepared miniaturized devices, and the sensory response was compared. EIS was performed in the frequency range between 1 Hz to 1 MHz to record the bacterial growth and activities as a function of change in electrical impedance, and detection performance of the different miniaturized devices with IDEs were compared. It was observed that the LIG-based IDE sensor provided better sensitivity compared to that of the other two approaches. The obtained results indicate that the magnitude of impedance changes by around 2.5 [Formula: see text] per doubling of E.coli cells. With fast and flexible fabrication process capabilities, such microdevices may be used as suitable IDE sensors for microscale pathogenic detection for biomedical and clinical analysis.

Enhanced low-dose x-ray sensing nature of nanocrystalline CaWO4 sensor

Extensive research on the development of superior sensitive X-ray sensors by many researchers is due to their increased demand in numerous fields, like medical radiography, security inspection, and scientific research areas. Especially in healthcare, repeated or long-term high-dose X-ray exposure on patients may cause serious health hazards. Therefore, developing a superior sensing low dose X-ray sensor is essential. In this present work, a nanocrystalline CaWO4 thick film above an interdigitated electrode was developed as a direct conversion X-ray sensor that operates at different low doses (mGy) using an intraoral pulsed X-ray (70 keV) machine. The X-ray instigated photocurrent of nano-CaWO4 thick film was examined under different applied bias to obtain superior sensitivity of the device. The nano-CaWO4 thick film exhibit sensitivity of 10 nC/mGycm3 at 0.20 mGy (0.06 s) low dose under 5 V applied bias. A suitable mechanism was proposed to explain the nano-CaWO4 thick film sensing behaviour at different biased conditions.

A Transparent Conductive Layer with an Interdigitated Electrode and Its Effect on Heat Generation

在這篇論文中，基於銦錫氧化物(ITO)加熱裝置依然存在許多問題，為了解決問題，本論文使用不同比例的指叉狀電極遮罩來蒸鍍電極在ITO上，並對其做深入研究。<br>在我們會使用到熱蒸鍍機，並以鋁作為電極，蒸鍍在ITO玻璃上，使用不比例的指叉狀遮罩來蒸鍍鋁於ITO的系統，其中指叉狀電極的比例分別為為1:1(sample02)，2:1(sample03)，3:2(sample04)，以及無指叉狀的電極(sample01)，而在這次的實驗中，我們所改變的參數只有指叉狀電極的比例，其他的參數則沒有改變，鋁圈數量是固定四圈，蒸鍍環境也都是固定的真空值，蒸鍍電流則是固定在70A，以便探討不同電極的影響。<br>在蒸鍍結束後，我們分別對不同比例指叉狀電極的樣品進行電學特性以及溫升的量測，結果表明1:1的電阻值約為68Ω，溫升速率約為0.617°C/s，2:1的電阻值約為100Ω，溫升速率約為0.335°C/s，3:2的電阻值約為100Ω，溫升速率約為0.314°C/s，1:1的電阻值是最小的，溫升速率是最快的，相較於其它比例的樣品是最高的，在蒸鍍不同指叉狀電極的時候，並不是電極數越多越好，而要考慮有效發熱面積與其他因素。In this paper, based on the existing ITO heating device, the effect is not as good as expected. Therefore, we use different types of metal masks to evaporate the electrode on a single layer of indium tin oxide (ITO). Do in-depth research, and this experiment is mainly divided into two parts. <br>In the first part, we will use a thermal evaporator, and use aluminum as the electrode to evaporate on the ITO glass, and use a non-proportional interdigitated mask to evaporate the aluminum on the ITO system. The proportion of the interdigitated electrode is They are 1:1 (sample2), 2:1 (sample3), 3:2 (sample4), and non-digital electrodes (sample1). In this experiment, the only parameter we changed was the fingers. The ratio of the shaped electrodes and other parameters have not changed. The number of aluminum circles is fixed four circles, the evaporation environment is also a fixed vacuum value, and the evaporation current is fixed at 70A to explore the influence of different electrodes. <br>After the evaporation, we measured the electrical characteristics and temperature rise of samples with different ratios of interdigitated electrodes. The results showed that the 1:1 resistance value is about 68Ω, and the temperature rise rate is about 0.617°C/s. 2:1 resistance value is about 100Ω, temperature rise rate is about 0.335°C/s, 3:2 resistance value is about 100Ω, temperature rise rate is about 0.314°C/s, 1:1 resistance value is the smallest Yes, the temperature rise rate is the fastest, which is the highest compared to other proportions of samples. When evaporating different interdigitated electrodes, it is not that the more electrodes are better, but the effective heating area and other factor.

ZnO based NOx gas and VOC detection sensor fabrication techniques and materials

Nano- or micro-nano gas sensors have attracted a lot of attention since they have the potential for several applications. Utilizing a coplanar integrated design of the microheater and the inter-digitated electrode, a chemo resistive ethanol gas sensor with a thin layer of zinc oxide (ZnO) as a sensing layer has been examined (IDE). The article's conclusion offers potential future paths and research opportunities for improved sensitivity and selectivity for these sensors. SnO2-based sensors have received a lot of attention in the field of hazardous gas detection because of their extraordinary sensitivity. ZnO thin films are created using a chemical method. Gas sensors must have reduced packaging because they are essential in modern industry for managing environmental concerns. Since the gas sensor must operate at temperatures higher than ambient temperature, using the heater is necessary. The heating mechanism for the detecting layer in the various gas sensors that have recently been developed is either external or incorporates additional layers. The suggested architecture might be helpful in cutting down on the number of layers that must be deposited for the sensor and additional heating circuits. A new architecture with a coplanar microheater and IDEs has been created to analyse the gas response. The ongoing work is built on the coplanar microheater with IDEs produced for the ethanol sensor. Additionally, studies have been conducted to examine how the sensor's sensing capabilities are impacted by the integrated architecture. The sensor detects a layer thickness of 430 nm with a sensing response of 110 the sensing layer is active over the substrate. The study's major goal is to show how an integrated coplanar microheater and IDE architecture may be used with ethanol sensor based on ZnO.

CeO2NPs Based Capacitive Sensor for Quantification of Limonin in Citrus Limetta Juice

Citrus fruit juices are beneficial to health immunity due to having antiviral, antifungal, and antioxidant properties. However, acceptability of its juices reduces due to the delayed bitterness caused mainly by the biomolecule limonin. Hence, continuous monitoring of limonin in juices is required to keep its limit within permissible level. Here, CeO2 nanoparticles (NPs) based capacitive sensor has been introduced for the first time to quantify limonin concentration in citrus limetta juice. The CeO2NPs were synthesized through a low-cost and eco-friendly method using Dillenia Indica aqueous extract. The capacitive sensor was designed and simulated using COMSOL multiphysics and fabricated by drop coating of CeO2NPs on interdigitated electrode (IDE) structure patterned on paper substrate. The sensor exhibits an excellent sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim $ </tex-math></inline-formula> 9.62 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm 0.095 \mu \text{F}$ </tex-math></inline-formula> /ppm and a fast response time of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim $ </tex-math></inline-formula> 13 s. The sensor’s performance was validated using high-performance liquid chromatography (HPLC) analysis. The developed sensor assures easy, on-site, eco-friendly, and rapid monitoring of limonin level in citrus juices.

Chemically derived graphene quantum dots for high-strain sensing

Graphene quantum dots (GQDs) refer to graphene fragments with a lateral dimension typically less than 100 nm, which possess unique electrical and optical properties due to the quantum confinement effect. In this study, we demonstrate that chemically derived graphene quantum dots show great potential for making highly stretchable and cost-effective strain sensors via an electron tunneling mechanism. Stretchable strain sensors are critical devices for the field of flexible or wearable electronics which are expected to maintain function up to high strain values (> 30%). However, strain sensors based on conventional materials (i.e. metal or semiconductors) or metal nanoparticles (e.g. gold or silver nanoparticles) only work within a small range of strain (i.e. the former have a working range < 1% and the latter < 3%). In this study, by simply dropcasting solution-processed GQDs between the interdigitated electrodes on polydimethylsiloxane, we obtained devices that can function in the range from 0.06% to over 50% tensile strain with both the sensitivity and working range conveniently adjustable by the concentration of GQDs applied. This study provides a new concept for practical applications of GQDs, revealing the potential of this material for smart applications such as artificial skin, human-machine interfaces, and health monitoring.

Recent Advances in CMOS Electrochemical Biosensor Design for Microbial Monitoring: Review and Design Methodology.

Rapid, high-sensitivity, and real-time characterization of microorganisms plays a significant role in several areas, including clinical diagnosis, human healthcare, early detection of outbreaks, and the protection of living beings. Integrating microbiology and electrical engineering promises the development of low-cost, miniaturized, autonomous, and high-sensitivity sensors to quantify and characterize bacterial strains at various concentrations. Electrochemical-based biosensors are receiving particular attention in microbiological applications among the different biosensing devices. Several approaches have been adopted to design and fabricate cutting-edge, miniaturized, and portable electrochemical biosensors to track and monitor bacterial cultures in real time. These techniques differ in their sensing interface circuits and microelectrode fabrication. The goals of this review are (i) to summarize the current state of CMOS sensing circuit designs in label-free electrochemical biosensors for bacteria monitoring and (ii) to discuss the material and size of the electrodes used in electrochemical biosensors in microbiological applications. In this paper, we reviewed the latest and most advanced CMOS integrated interface circuits that have recently been used in electrochemical biosensors to identify and characterize bacteria species, such as impedance spectroscopy, capacitive, amperometry, and voltammetry, etc. In addition to the interface circuit design, other crucial factors, such as the material and scale of the electrodes, must be considered to increase the sensitivity of electrochemical biosensors. Surveying the literature in this field improves our knowledge about the impact of electrode designs and materials on sensing precision and will help future designers adapt, design, and fabricate appropriate electrode configurations based on their application. Thus, we summarized the conventional microelectrode designs and materials mainly employed in microbial sensors, including interdigitated electrodes (IDEs), microelectrode arrays (MEAs), paper, and carbon-based electrodes, etc.

Rapid and Visual Detection of Oxytetracycline Using Mesoporous Silica Nanochannels Modified Interdigital Electrode

Oxytetracycline (OTC) is one of the widely used antibiotics in veterinary practices because of its broad-spectrum antibacterial activity and low cost. However, drug abuse has triggered adverse effects on human health, which brings a growing demand for on-site diagnosis of OTC residues in animal-derived foods. In this study, we demonstrated the combined use of interdigital electrode microarray and electrochemiluminescence (ECL) imaging for parallel multiplex measurement of OTC. Well-ordered and vertically aligned mesoporous silica nanochannels modified on microarray substrate could exert a strong electrostatic attraction to the ECL luminophores and accelerate their mass transport to generate enhanced ECL signal. The performance of the integrated ECL microarray sensor was fully validated with respect to linearity (0.5 μM to 50 μM), sensitivity (limit of detection 0.26 μM), accuracy (recovery rate between 96.78% and 106.1%), low operating sample volume (480 nL), short assay time (1.5 min), and antifouling ability toward complex media. The multiplex microarray platform can serve as a simple, fast, and low-cost tool for the detection of a wide spectrum of antibiotics in the field of food safety.

Dual-Function Smart Windows Using Polymer Stabilized Cholesteric Liquid Crystal Driven with Interdigitated Electrodes.

In this study, we present an electrically switchable window that can dynamically transmit both visible light and infrared (IR) light. The window is based on polymer stabilized cholesteric liquid crystals (PSCLCs), which are placed between a top plate electrode substrate and a bottom interdigitated electrode substrate. By applying a vertical alternating current electric field between the top and bottom substrates, the transmittance of the entire visible light can be adjusted. The cholesteric liquid crystals (CLC) texture will switch to a scattering focal conic state. The corresponding transmittance decreases from 90% to less than 15% in the whole visible region. The reflection bandwidth in the IR region can be tuned by applying an in-plane interdigital direct current (DC) electric field. The non-uniform distribution of the in-plane electric field will lead to helix pitch distortion of the CLC, resulting in a broadband reflection. The IR reflection bandwidth can be dynamically adjusted from 158 to 478 nm. The electric field strength can be varied to regulate both the transmittance in the visible range and the IR reflection bandwidth. After removing the electric field, both features can be restored to their initial states. This appealing feature of the window enables on-demand indoor light and heat management, making it a promising addition to the current smart windows available. This technology has considerable potential for practical applications in green buildings and automobiles.

Combining Impedance Spectroscopy and Information Visualization Methods to Optimize the Detection of Carbendazim Using Layer-by-Layer Films

Usually, electronic tongues (e-tongue) do not require specific interactions to discriminate aqueous solutions. Among the several factors which determine the electrical properties of sensing units, the interactions between liquids and interfaces have a crucial role. Here, we explore the interaction between dioctadecyldimethylammonium bromide (DODAB) lipid and carbendazim (MBC) pesticide in an e-tongue to discriminate different MBC concentrations in aqueous solutions. The sensing units were fabricated of gold interdigitated electrodes (IDEs) coated with layer-by-layer (LbL) films of DODAB and nickel tetrasulfonated phthalocyanine (NiTsPc), perylene and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (DPPG), namely (DODAB/NiTsPc)5 and (Perylene/DPPG)5, respectively. Besides, a bare electrode also constituted the e-tongue to distinguish MBC concentrations from 1.0 × 10−7 up to 1.0 × 10−10 mol L−1, by impedance spectroscopy. In addition, the experiment was optimized using two IDE geometries. The LbL films were manually fabricated obtaining linear growth monitored via UV-Vis absorption spectroscopy. Optical images associated with chemical mapping reveals the presence of small aggregates in the DODAB/NiTsPc LbL film surface. Although the e-tongue was able to discriminate all MBC concentrations by means of the interactive document map (IDMAP), only the sensing unit covered with DODAB/NiTsPc LbL film presented a satisfactory response. According to the equivalent circuit, the main contribution arises from the bulk and film surface due to the interaction between DODAB and MBC, indicating THE sensitivity of the sensing unit. Finally, the adsorption of MBC molecules onto the film surface induced an irreversible process, although there are some frequencies at which the sensing unit response seems to be reversible, as shown by parallel coordinates.

An efficient cobalt-nickel phosphate positive electrode for high-performance hybrid microsupercapacitors

Flexible energy storage devices play significant role in wearable and portable electronics. Herein, a cobalt-nickel phosphate (CoNiP2O7) composite was synthesized on conductive carbon nanotubes (CNTs) substrate by facile one-step electrochemical deposition method, forming a binder-free CoNiP2O7@CNTs positive electrode for microsupercapacitors (MSCs). Combined with a CNTs substrate on the opposite side of interdigitated electrodes, a CoNiP2O7@CNTs//CNTs hybrid MSC device was assembled. It displayed good electrochemical performance with a largest areal capacitance of 20.9 mF·cm−2 at 0.08 mA·cm−2 and an energy density of 2.9 μWh·cm−2. To construct a self-powered solar cell energy storage system, the proposed MSC device was utilized for energy storage and further provided power for red light-emitting diode (LED), forming natural energy collection-conversion-storage-utilization system. The results of this study offer a simple design route for flexible energy storage devices.

Ideal micro-lenticular lens based on phase modulation of optically isotropic liquid crystal-polymer composite with three terminals

Optical phase modulation in a transparent polymer film composed of nano-sized liquid crystal (LC) droplets embedded within a polymer matrix exhibits a micro-lenticular lensing effect under controlled in-plane field switching (IPS) with interdigitated electrodes. Despite of the lensing effect, the lens profile does not match ideal one and its effective phase modulation is relatively small owing to the weak field strength over the electrodes, which causes an invariant refractive index in these regions. To achieve ideal lens profile and high phase modulation, a vertical electric field is applied between top plane and bottom interdigitated electrodes, while maintaining the in-plane fields between the bottom interdigitated electrodes. The combined effect, referred to as the vertical and in-plane switching (VIS) mode, can achieve larger phase modulation (Δδ) than the IPS mode. Consequently, the proposed micro-lenticular lens has a shorter focal length and a significantly better lens profile, similar to the ideal one. Furthermore, the diffraction efficiency (Df) is effectively improved by ∼ 6.7%, 4%, and 2% for the zeroth (0th), ±1st, and ± 2nd orders, respectively, compared to those in the IPS mode. The improved phase profile with the proposed micro-lenticular device can be used in a switchable lens from 2-dimensions (2D) to 3-dimension (3D) and tunable diffractors.

Direct ink writing of PEDOT:PSS inks for flexible micro-supercapacitors

Here, we fabricate poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)-based flexible micro-supercapacitors (MCSs) using direct ink writing (DIW) printing. To produce inks suitable for DIW printing, inks with various PEDOT:PSS concentrations are prepared, and their rheological properties and printability are systematically investigated. The optimized PEDOT:PSS ink allows stable printing without spreading and nozzle clogging issues, leading to the successful fabrication of well-defined interdigitated electrode patterns. The resulting PEDOT:PSS-based MSC exhibits high energy storage performance (2005 μF/cm2 at 10 μA/cm2) and outstanding cycle stability (capacitance retention of 87% after 10,000 cycles). Taking advantage of the flexibility of the PEDOT:PSS electrode, the MSC maintains its performance even under bending stress. Moreover, the practicality of the system is demonstrated by tailoring the overall operating voltage and output capacitance through printing MSCs connected in series and parallel.

SLA printing of POSS-containing, bio-based composites with low dielectric constant and shape-memory function

Improving sustainability and functionality of resins is important for the development of 3D printing technologies. This work demonstrates a novel bio-based and low dielectric resin containing polyhedral oligomeric silsesquioxane (POSS) for stereolithography (SLA) printing to fabricate sensors and shape memory materials with complex geometry. Epoxidized soybean oil (ESO) and methacrylic acid are used to synthesize a biobased methacrylate resin (MESO) via a ring-opening reaction, followed by incorporation of POSS into polymer matrix. In general, the viscosity of POSS/MESO composite resins is in the range of 0.40–0.58 Pa s, making them viable for SLA printing designs. With the addition of 5 wt% POSS, POSS/MESO composites can exhibit excellent mechanical properties, including tensile strength (18.9 MPa), elongation at break (19.8%), and toughness (399.2 MJ/m3). Furthermore, these materials have a very low dielectric constant of 2.97 at 1 MHz, which is desired for microelectronic applications to overcome signal delay and energy loss. In addition, presence of permanent and reversible networks formed by MESO and POSS endows the POSS/MESO composites with good shape memory property. The application demonstrators include fabrication of flexible interdigital electrode sensors and temperature-responsive sensors. Overall, this work provides great potential opportunities to design the bio-based functional sensor with on-demand control over structures by SLA printing.

Heterogeneous Multi-Material Flexible Piezoresistive Sensor with High Sensitivity and Wide Measurement Range

Flexible piezoresistive sensors (FPSs) have the advantages of compact structure, convenient signal acquisition and fast dynamic response; they are widely used in motion detection, wearable electronic devices and electronic skins. FPSs accomplish the measurement of stresses through piezoresistive material (PM). However, FPSs based on a single PM cannot achieve high sensitivity and wide measurement range simultaneously. To solve this problem, a heterogeneous multi-material flexible piezoresistive sensor (HMFPS) with high sensitivity and a wide measurement range is proposed. The HMFPS consists of a graphene foam (GF), a PDMS layer and an interdigital electrode. Among them, the GF serves as a sensing layer, providing high sensitivity, and the PDMS serves as a supporting layer, providing a large measurement range. The influence and principle of the heterogeneous multi-material (HM) on the piezoresistivity were investigated by comparing the three HMFPS with different sizes. The HM proved to be an effective way to produce flexible sensors with high sensitivity and a wide measurement range. The HMFPS-10 has a sensitivity of 0.695 kPa−1, a measurement range of 0–14,122 kPa, fast response/recovery (83 ms and 166 ms) and excellent stability (2000 cycles). In addition, the potential application of the HMFPS-10 in human motion monitoring was demonstrated.

Microfluidic Channel-Based Soft Electrodes and Their Application in Capacitive Pressure Sensing.

Flexible and stretchable electrodes are essential components in soft artificial sensory systems. Despite recent advances in flexible electronics, most electrodes are either restricted by the patterning resolution or the capability of inkjet printing with high-viscosity super-elastic materials. In this paper, we present a simple strategy to fabricate microchannel-based stretchable composite electrodes, which can be achieved by scraping elastic conductive polymer composites (ECPCs) into lithographically embossed microfluidic channels. The ECPCs were prepared by a volatile solvent evaporation method, which achieves a uniform dispersion of carbon nanotubes (CNTs) in a polydimethylsiloxane (PDMS) matrix. Compared to conventional fabrication methods, the proposed technique can facilitate the rapid fabrication of well-defined stretchable electrodes with high-viscosity slurry. Since the electrodes in this work were made up of all-elastomeric materials, strong interlinks can be formed between the ECPCs-based electrodes and the PDMS-based substrate at the interfaces of the microchannel walls, which allows the electrodes to exhibit mechanical robustness under high tensile strains. In addition, the mechanical-electric response of the electrodes was also systematically studied. Finally, a soft pressure sensor was developed by combining a dielectric silicone foam and an interdigitated electrodes (IDE) layer, and this demonstrated great potential for pressure sensors in soft robotic tactile sensing applications.

Two-Dimensional Nanocrystal Assemblies for Photocapacitive Devices

We describe the emergence of photocapacitance in two-dimensional layered nanocrystal assemblies. Devices are electrically probed by the application of a lateral bias across interdigitated electrodes. We observe capacitive current–voltage characteristics that are individually absent in the nanocrystals. Besides the occurrence of a large zero-bias capacitance, the assemblies further show a transient negative capacitive behavior where the small signal capacitance is found to attain values over a ±100 nF range. We show that this system behaves as a damped anharmonic oscillator. Further, the bias dependence of capacitance, characteristics under asymmetric cycling, as well as its relationship with shunt resistance are consistent with the system attaining a transient negative capacitance while migrating around a single energy minimum. We show modulation of the capacitive behavior by incident light enabling the usage of these materials in a photocapacitive detector device.

Fabrication of Rapid Electrical Pulse-Based Biosensor Consisting of Truncated DNA Aptamer for Zika Virus Envelope Protein Detection in Clinical Samples

Zika virus (ZV) infection causes fatal hemorrhagic fever. Most patients are unaware of their symptoms; therefore, a rapid diagnostic tool is required to detect ZV infection. To solve this problem, we developed a rapid electrical biosensor composed of a truncated DNA aptamer immobilized on an interdigitated gold micro-gap electrode and alternating current electrothermal flow (ACEF) technique. The truncated ZV aptamer (T-ZV apt) was prepared to reduce the manufacturing cost for biosensor fabrication, and it showed binding affinity similar to that of the original ZV aptamer. This pulse-voltammetry-based biosensor was composed of a T-ZV apt immobilized on an interdigitated micro-gap electrode. Atomic force microscopy was used to confirm the biosensor fabrication. In addition, the optimal biosensor performance conditions were investigated using pulse voltammetry. ACEF promoted aptamer-target binding, and the target virus envelope protein was detected in the diluted serum within 10 min. The biosensor waveform increased linearly as the concentration of the Zika envelope in the serum increased, and the detection limit was 90.1 pM. Our results suggest that the fabricated biosensor is a significant milestone for rapid virus detection.