Variation Of Electrical Properties Research Articles

Rapid Degradation of the Electrical Properties of 2D MoS2 Thin Films under Long-Term Ambient Exposure.

The MoS2 thin film has attracted a lot of attention due to its potential applications in flexible electronics, sensors, catalysis, and heterostructures. Understanding the effect of long-term ambient exposure on the electrical properties of the thin film is important for achieving many overreaching goals of this material. Here, we report for the first time a systematic study of electrical property variation and stability of MoS2 thin films under ambient exposure of up to a year. The MoS2 thin films were grown via the sulfurization of 6 nm thick molybdenum films. We found that the resistance of the samples increases by 114% just in 4 weeks and 430% in 4 months and they become fully insulated in a year of ambient exposure. The dual-sweep current–voltage (I–V) characteristic shows hysteretic behavior for a 4-month-old sample which further exhibits pronounced nonlinear I–V curves and hysteretic behavior after 8 months. The X-ray photoelectron spectroscopy measurements show that the MoS2 thin film gradually oxidizes and 13.1% of MoO3 and 11.8% oxide of sulfur were formed in 4 months, which further increased to 23.1 and 12.7% in a year, respectively. The oxide of the sulfur peak was not reported in any previous stability studies of exfoliated and chemical vapor deposition-grown MoS2, suggesting that the origin of this peak is related to the distinct crystallinity of the MoS2 thin film due to its smaller grain sizes, abundant grain boundaries, and exposed edges. Raman studies show the broadening of E2g1 and A1g peaks with increasing exposure time, suggesting an increase in the disorder in MoS2. It is also found that coating the MoS2 thin film with polymethylmethacrylate can effectively prevent the electrical property degradation, showing only a 6% increase in resistance in 4 months and 40% over a year of ambient exposure.

Understanding and minimizing resonance frequency deviations on a 4-in. kilo-pixel kinetic inductance detector array

One of the advantages of kinetic inductance detectors is their intrinsic frequency domain multiplexing capability. However, fabrication imperfections usually give rise to resonance frequency deviations, which create frequency collision and limit the array yield. Here, we study the resonance frequency deviation of a 4-in. kilo-pixel lumped-element kinetic inductance detector (LEKID) array using optical mapping. Using the measured resonator dimensions and film thickness, the fractional deviation can be explained within ±25×10−3, whereas the residual deviation is due to variation of electric film properties. Using the capacitor trimming technique, the fractional deviation is decreased by a factor of 14. The yield of the trimming process is found to be 97%. The mapping yield, measured under a 110 K background, is improved from 69% to 76%, which can be further improved to 81% after updating our readout system. With the improvement in yield, the capacitor trimming technique may benefit future large-format LEKID arrays.

P-type conductivity and suppression of green luminescence in Mg/N co-implanted GaN by gyrotron microwave annealing

Co-implantation of Mg with N has been shown to improve p-type conductivity in Mg-implanted GaN. Achievement of p-type material still requires temperatures beyond the thermodynamic stability of GaN, however. In this study, we present results of implantation and anneal activation of GaN, co-implanted with Mg and N or Mg only by repeated, short thermal cycles of 1350 °C using a high-power gyrotron microwave source with a quasi-gaussian intensity profile. Spatial variations in optical and electrical properties of the resulting films are characterized by photoluminescence and diode I–V and C–V measurements. Resistive Mg/N co-implanted and annealed material shows dominant luminescence of the VN-related green luminescence (GL2) band at 2.37 eV and relatively lower intensity acceptor-related ultraviolet luminescence (UVL) at 3.27 eV. However, a material showing p–n diode behavior shows higher-intensity UVL luminescence and suppression of the GL2 band, permitting observation of the yellow luminescence (YL) present in the as-grown GaN. The YL is attributed to unintentionally introduced CN–ON complexes and is commonly observed in GaN grown by metalorganic chemical vapor deposition but is typically absent in implanted/annealed GaN. Co-implanted material is compared to material implanted only with Mg and annealed under the same conditions, which shows p-type activation, but contains persistent GL2 luminescence post-anneal and lowers maximum hole concentration.

Negative Bias Instability of InZnO-Based Thin-Film Transistors Under Illumination Stress.

In this study, we investigated the threshold voltage (Vth) instability of solution-processed indium zinc oxide (IZO) thin film transistors (TFTs) prior to and after negative bias illumination stress (NBIS) with varying carrier suppressors (Ga, Al, Hf, and Zr). Variations in electrical properties of the IZO-based TFTs as a function of carrier suppressors were attributed to the differences in metal-oxygen bonding energy of the materials, which was numerically verified by calculating the relative oxygen deficient ratio from the X-ray photoelectron spectroscopy analysis. Furthermore, the values of Vth shift (ΔVth) of the devices subjected to negative gate bias stress under 635 nm (red), 530 nm (green), and 480 nm (blue) wavelength light irradiation increased as the incident photon energy increased. IZO TFTs doped with Ga atoms demonstrated weaker metal-oxygen bonding energy compared to the others and exhibited the largest ΔVth. This result was attributed to the suppressor-dependent distribution of neutral oxygen vacancies which determine the degrees of photon energy absorption in the IZO films. Then, the ΔVth instability of IZO-based TFTs under NBIS correlated well with a stretched exponential function.

Electrodermal Activity (EDA) and body temperature Monitoring system for patients with psychological disorder

In today’s world we are leading an unimaginably fast and stressful life. Hence, the number indicating psychological disorder cases has hiked like never before. Compared to physiological disorders, psychological disorders take longer time to cure and mandates long term monitoring the patient in his/her daily and personal life. Galvanic Skin Resistance (GSR), also called Electrodermal Activity (EDA) is actually measurement of variations in electrical properties of skin attributed to Sympathetic Nerve System (SNS), directly related to mental state of the subject, such as stress, drowsiness and engagement. We have put an effort in making a wearable device to monitor such important parameter. The device is designed using silver electrodes, LMT70 temperature sensor and Arduino mini pro. The device is capable of recording EDA and body temperature periodically at an interval of 5 minutes for 7 days on a single charge of 3000mAh battery of 3.3V. The data is recorded on a microSD card in CSV format.

Etching Time on Structural and Electrical Properties of Porous Silicon SERS Substrates for Non-Invasive Dengue-NS1 Detection

: Surface Enhanced Raman Spectroscopy (SERS) is a sensitive and specific analytical technique which has been explored in many applications, including disease detection. However, SERS performance is highly dependent on type of SERS substrate. This work is aimed to develop a SERS substrate that is sensitive to an early dengue virus biomarker known as Dengue virus nonstructural 1 (DENV-NS1) protein from saliva of infected patients. The new SERS substrate will allow non-invasive and rapid detection method for Dengue as early as day one of infection. Early detection of infection within the first five days is crucial to monitoring patients to help in reducing the fatality rate. Here, the electrochemical etching technique is employed to fabricate porous silicon (pSi) with variation in structural features to serve as the SERS substrate base. Variation in surface structural and electrical properties of pSi with etching time is recorded. Structural surface properties of the samples are investigated using the Field Emission Scanning Electron Microscope (FESEM) and energy-dispersive X-ray spectroscopy (EDX). While the electrical properties are observed through I-V, resistivity and conductivity curve. From FESEM images, micro size cross-shaped porous structures are observed to have formed. Top-view reveals micro-size cross-shaped structures, while triangle-shaped structures from the cross-sectional view. The size of the structure formed increases with the etching time. Based on the structural and electrical properties an etching time between 20 to 28 minutes is found optimal for producing more uniform surface structures.

Effects of gamma irradiation on GaN high-electron-mobility transistors characterized by the voltage-transient method

The effects of gamma irradiation on the electrical and trapping properties of AlGaN/GaN high-electron-mobility transistors (HEMTs) are investigated in detail. During the irradiation, the gate–source leakage current of the HEMT is monitored online when applying a reverse gate voltage. The variations of electrical properties of the device, including an increase in drain–source current, the negative threshold voltage shift, and a decrease of leakage current, are observed. In particular, three traps in the device are identified using the voltage-transient method and the variations of these traps after irradiation are also investigated. The results show that the absolute amplitudes of the three traps in the device decrease after irradiation, which indicates a reduction in the density of the traps. Furthermore, it is proposed that the time constants and energy levels of the three traps decrease after irradiation. The observed changes in the trapping behaviors are ascribed to the structural ordering of the defects, which is consistent with the improvement in the electrical characteristics of the device.

Enhancing the reactivity of carbon-nanotube for carbon monoxide detection by mono- and co-doping of boron and nitrogen heteroatoms: A DFT and TD-DFT study

Carbon nanotube (CNT) doped with boron (p-type) and nitrogen (n-type) atoms (BxNy@CNT) have attracted the attention of many experimental and theoretical researchers for variety of industrial applications such as catalytic processes in fuel cells and detection of environmental pollutants. BxNy@CNTs can be synthesized with different concentrations (i.e. x/y ratios) and various configurations (i.e. relative position of B to N atoms), and therefore, BxNy@CNTs show an unpredictable reactivity in physical and chemical reactions. Hence, the selection of an appropriate BxNy@CNTs combination to achieve the most efficiency for a specific application is a challenge for experimentalists. In this regard, herein, we investigated theoretically different combinations of BxNy@CNT (x, y = 0, 1), i.e. single doped boron (B@CNT) and nitrogen (N@CNT) along with multi-doped boron and nitrogen BN@CNT, in three ortho, meta and para-BN@CNT configurations for detection and removing of monoxide carbon (CO) as a diatomic toxic gas. Theoretical calculations were done based on the quantum calculations in DFT and TD-DFT levels of theory using M06-2X (and B3LYP-D3)/6-31+G(d,p) functional/basis set. We focused on variations in electrical (useable for electronic based nano-sensor devices) and optical (useable for optical based nano-sensor devices) properties after adsorption of CO gas. Results indicate that, compared to the other combinations, co-doping of boron in para position relative to nitrogen (para-BN@CNT) can significantly activate the inert-CNT toward CO sensing. Theoretical results of this work can help experimental scientists in the synthesis and selection of the appropriate BxNy@CNT combinations for applying in nanotube based nano-sensors.

Studies on electrical properties of Fe doped ZnO nanostructured oxides synthesized by sol–gel method

We report the results of the studies on electrical properties of Zn1–xFexO (x = 0.10, 0.15 and 0.20) nanoparticles synthesized using sol–gel method. X–ray diffraction (XRD) measurement confirms the presence of extra phase of ZnFe2O4 in all the samples which gets enhanced with increase in Fe concentration. Surface morphological studies using atomic force microscopy (AFM) suggest the reduction in grain size with increase in Fe doping level in ZnO. All the dielectric parameters show dispersion nature and dielectric constant has been found to increase with Fe content. The obtained dielectric behavior has been understood on the basis of Maxwell–Wagner (M − W) mechanism and Koop's theory. Frequency dependent electrical conductivity has been understood on the basis of Jonscher's universal power law that suggests a conduction of charge carrier through correlated barrier hopping (CBH) mechanism. Impedance spectroscopy measurements have been explained on the basis of crystal cores and crystal boundary density. Grain boundary contribution in conduction mechanism is identified by fitting equivalent circuit model on cole–cole plots. Temperature and magnetic field dependent variation in electrical properties of studied samples has been understood on the basis of structure–property correlations.

Interfacial polarization of in vivo rat sciatic nerve with crush injury studied via broadband dielectric spectroscopy.

Electrical stimulation is one of the candidates for elongation-driven regeneration of damaged peripheral nerves. Different organs and tissues have an inherent cell structure and size. This leads to variation in the tissue-specific electrical properties of the frequency of interfacial polarization. Although nervous tissues have a membrane potential, the electrical reaction inside these tissues following electrical stimulation from outside remains unexplored. Furthermore, the pathophysiological reaction of an injured nerve is unclear. Here, we investigated the electrical reaction of injured and non-injured rat sciatic nerves via broadband dielectric spectroscopy. Crush injured and non-injured sciatic nerves of six 12-week-old male Lewis rats were used, 6 days after infliction of the injury. Both sides of the nerves (with and without injury) were exposed, and impedance measurements were performed at room temperature (approximately 25°C) at frequencies ranging from 100 mHz to 5.5 MHz and electric potential ranging from 0.100 to 1.00 V. The measured interfacial polarization potentially originated from the polarization by ion transport around nerve membranes at frequencies between 3.2 kHz and 1.6 MHz. The polarization strength of the injured nerves was smaller than that of non-injured nerves. However, the difference in polarization between injured and non-injured nerves might be caused by inflammation and edema. The suitable frequency range of the interfacial polarization can be expected to be critical for electrical stimulation of injured peripheral nerves.

Regional variation of electrical and lightning properties of thunderclouds during the pre-monsoon season over the north-eastern and eastern part of India

Regional variation of electrical and lightning properties of thunderclouds is investigated by using simultaneous observations of electric field mill (EFM-100) and lightning detector (LD-350) in synergy with their radiance and bulk microphysical properties. The study is carried out over Kohima in the north-eastern and over Rampurhat in the eastern part of India (20o-30o N, 85o-96o E), during the pre-monsoon season (March–May) of 2017–2018. The occurrence of EFM-100 detected thunderclouds is found to be more over Kohima (111) compared to Rampurhat (88). Whereas, the average number of lightning flash is much higher over Rampurhat (~542 flash/thundercloud) compared to Kohima (~32 flash/thundercloud). Over both the regions, the maximum occurrence of thunderclouds is found during afternoon to evening hours. The upper whisker value in the box plot shows that thunderclouds over Rampurhat are associated with higher CAPE value (Kohima: 1100 J Kg−1; Rampurhat: 5000 J Kg−1). The diurnal variation of CAPE supports relatively early occurrence of thunderclouds over Kohima. Thunderclouds over Rampurhat persists for relatively longer duration. It is observed that overall percentage occurrence of CG lightning is more over Kohima (Kohima: −CG: 28.09% & +CG: 09.74%; Rampurhat (–CG: 12.33% & +CG: 08.60%), with relatively higher −CG lightning compared to +CG, over both the stations. On the contrary, the occurrence of IC lightning is more over Rampurhat (Rampurhat: −IC: 31.75% & +IC: 47.30%; Kohima: −IC: 36.44% & +IC: 25.72%). Over Kohima occurrence of −IC is more than the +IC, whereas over Rampurhat, the occurrence of +IC is more than −IC. The overall higher occurrence of total negative and positive discharges over Kohima and Rampurhat respectively is consistence with EFM observations. The prevalence of positive/negative discharge suggests the presence of a tripole charge structure within thunderclouds over both the regions. The upper whisker value in the box plots revels higher CG flash density, IC:CG and larger log(area) over Rampurhat (Kohima: 3.0 × 10−3 flash km−2 h−1 and Rampurhat: 4.25 × 10−3 flash km−2 h−1; Kohima: 7 and Rampurhat: 15; Kohima: 10.5 km2 and Rampurhat: 11.5 km2). The lower whisker value of cloud top temperature reveals prevalence of colder thunderclouds over Rampurhat (Kohima: 220 K; Rampurhat: 184 K). The thunderclouds over Rampurhat are found to be associated with stronger updrafts and mixed-phase processes. The study reveals that, over these two regions, the electrical and lightning properties have distinct characteristics.

Application of electrical resistivity to map the stratigraphy and salinity of fluvio-deltaic aquifers: case studies from Bangladesh that reveal benefits and pitfalls

Fluvio-deltaic aquifers are the primary source of drinking water for the people of Bangladesh. Such aquifers, which comprise the Ganges-Brahmaputra-Meghna Delta, are hydrogeologically heterogeneous. Because of widespread groundwater quality issues in Bangladesh, it is crucial to know the hydrostratigraphic architecture and hydrochemistry, as some aquifer units are contaminated, whereas others are safe. Geophysical methods provide a potentially effective and noninvasive method for extensive characterization of these aquifers. This study applies and investigates the limitations of using electrical resistivity imaging (ERI) for mapping the hydrostratigraphy and salinity of an aquifer-aquitard system adjacent to the Meghna River. Some electrical resistivity (ER) sections showed excellent correlation between resistivity and grain size. These suggest that ERI is a powerful tool for mapping internal aquifer architecture and their boundaries with finer-grained aquitards which clearly appear as low-ER zones. However, in parts of some ER sections, variations in electrical properties were determined by porewater resistivity. In these cases, low ER was indicative of brine and did not indicate the presence of finer-grained materials such as silt or clay. Accordingly, the following hydrostratigraphic zones with different resistivities were detected: (1) aquifers saturated with fresh groundwater, (2) a regional silt/clay aquitard, and (3) a deeper brine-saturated formation. In addition, shallow silt/clay pockets were detected close to the river and below the vadose zone. ERI is thus a promising technique for mapping aquifers versus aquitards; however, the observations are easily confounded by porewater salinity. In such cases, borehole information and groundwater salinity measurements are necessary for ground-truthing.

Taking into account the spatial variability of the physical and mechanical properties of a hydraulic dump when flushing it

Introduction. Slope stability analysis reliability depends on the level of schematizing the results of engineering-geological survey, hydrogeological monitoring, electrical sounding, and mine surveying data generalization. In order to improve the stability analysis accuracy, it is relevant to use the geomechanical models, which take into account the spatial variability of the adjacent rock mass physical and mechanical properties, with further search for the most hazardous section in the plan. Research aim is to substantiate the relevance of slopes physical and mechanical monitoring by the methods of downhole control and further stability analysis with the use of the geological and geophysical models. Methodology includes the search for the most hazardous section of the rock mass by the ratio of the shearing and restraining forces within the limits of the established zones characterized by the variability of physical and mechanical properties. Results. As a result of generalizing the databases of the engineering and geological study, hydrogeological monitoring, electrical sounding and mine surveying, the volumetric geological and geophysical models were built of the technogenic massif formed at the dump, as well as the slopes of the hydraulic overburden face, represented by the three-level fill of dry overburden. Test areas stability has been analyzed for the actual position, and the comparative analysis of the results was made. Conclusions. When building volumetric geological and geophysical models of man-made rock masses formed at the areas of filled hydraulic waste diposals, in addition to the results of the traditional survey measurements and direct engineering and geological study, it is important to create informative databases on spatial and temporal variations of physical and mechanical properties of alluvial rock conditioned by their fluid loss and consolidation, which with in details at cross hole intervals may be obtained based on the statistical dependences on electrical conductive properties variation by the methods of electrical sounding or tomography; and when making enclosing embankments (bridges) of dry rocks – information about excess pore pressure under these facilities. When using the hydromechanized method for the alluvial rocks, relatively homogeneous in strength properties, the hydraulic overburden face slope stability is determined to the greatest extent by the absolute values of the accumulated strength indicators in the mined area and the unfavorable combination of the edge shape (the presence of protruding sections and face unevenness in the plan) with the entry height. The established range of the stability coefficient was n = 1.03–3.76. The stability of the enclosing structures made of dry rock to the greatest extent depends on weak alluvial layer depth and thickness and the absolute value of excess pore pressure in this layer. The established range of stability coefficient variation for this rock mass section is much narrower and amounted to n = 1.29–1.59.

The effect of graphene structural integrity on the power factor of tin selenide nanocomposite

Tin selenide graphene nanocomposites (SnSe/GNPs) were fabricated with high-energy ball milling and hot pressing by varying the milling time of graphene. The effect of ball milling time on the graphene integrity and the dispersion homogeneity was investigated and the consequential variation in electrical properties of SnSe/GNPs were analyzed. The evolution of graphene sheets during milling as well as the crystal structure of SnSe/GNPs nanocomposites were systematically studied by X-ray diffraction, Raman analysis, scanning electron microscopy, and transmission electron microscopy. It has been proven that graphene was able to keep its crystallinity at short milling times, but it exhibits agglomeration and poor dispersion within the matrix. However, long milling time has a significant effect on increasing the disorders on graphene structure while it provides well dispersion of graphene. The calculated power factor increases with the addition of graphene and with increasing graphene milling time. The increased power factor is attributed to the homogeneous distribution of graphene, which results in a significant increase in electrical conductivity. At 773 K, the lowest power factor value was reported for the 1-min graphene-milled sample, whereas a 40% enhancement was reported for the 2-h graphene-milled sample. Across a wide temperature range (298–720 K), the 12-h graphene-milled sample shows the best performance owing to the simultaneous increase of electrical conductivity and Seebeck coefficient. These findings indicate the positive effect of milling time on the distribution of graphene, which in turn enables graphene to form a continuous net for carriers to move. This study could provide a greater understanding of the control factors of the mechanical milling process for preparing SnSe/GNPs nanocomposites in order to take full advantage of graphene’s extraordinary properties by improving its distribution within the tin-selenide- based composite.

Variation in electrical and structural properties of Ga-doped ZnO films caused by oxygen out-diffusion

Variation in electrical and structural properties of Ga-doped ZnO films caused by oxygen out-diffusion

Influence of oxygen flow during sputtering process on the electrical properties of Ga-doped InZnSnO thin film transistor

This work presents the electrical properties of amorphous gallium-doped indium zinc tin oxide (Ga-IZTO) thin film transistors (TFTs), as a function of O2 flow rate (Ar/O2), during the sputtering process of the channel layer. As the O2 flow rate increased from 30:0 to 30:7, the saturation mobility ( SAT) monotonically degraded from 31.5 cm2V−1s−1 to 12.0 cm2V−1s−1, the threshold voltage (V TH) shifted from 0.8 V to 6.8 V, and the V TH shift (ΔV TH) induced by the negative bias stress improved from −7.0 V to −2.8 V. X-ray diffraction analysis indicated that themicrostructure of all the films is amorphous, which is independent of O2 flow rate. Transmittance spectra reflected that the average transmittance of the thin film is sensitive to the O2 flow rate and decreases as the O2 flow rate increases. XPS analysis revealed that the density of oxygen vacancies is reduced, and the oxygen lattices are enhanced as the O2 flow rate increases. The Hall effect measurements indicated that the carrier concentration (n) was reduced with increasing O2 flow rate. These results show that the electrical properties of Ga-IZTO TFTs can be easily tuned by the O2 flow rate during the sputtering process. The related mechanism for the variations of electrical properties of Ga-IZTO TFT has been discussed in detail.

Thermal Distortion Compensation for Improving Electrical Performance of Reflector Antennas

Aiming at the problem of the surface accuracy and electrical performance of the antenna in space environment are reduced due to thermal deformation caused by temperature load. This paper presents a method to compensate the thermally induced shape distortion of antenna reflector by actively adjusting actuators in order to improve the electrical performance. The adjustment of each actuator is related to the local deformation of the panel. Then, taking a space deployable antenna with a diameter of 5 meters as an example, the finite element model is established. According to the range of the temperature variation in space (−180°C - 200°C), different temperature loads are applied to the antenna. The variation of electrical properties and surface accuracy is analyzed and the worst working condition is determined, and the antenna is compensated based on this condition. Then, four different electrical performance parameters are used as the optimization objectives, and the electromechanical coupling optimization model is established, and the PSO algorithm is used to optimize the actuators adjustments. The results show that the method can effectively improve the electrical performance of the deformed reflector antenna.

A Real-Time-Link-Adaptive Operation Scheme for Maximum Energy Storage Efficiency in Resonant CM Wireless Power Receivers

The development, analysis, and experimental validation of an energy storage algorithmic scheme for performance optimization of resonant inductive power receivers are presented. Motivated by the crucial role of efficient energy storage in the next generation of brain-implantable devices, we introduce an energy management strategy in the design of wireless powering links, in which, the key performance measure is the energy stored during a limited time interval rather than the average energy delivered to the load. The presented strategy is proven analytically to yield the theoretically-maximum energy storage efficiency over a pre-determined period of time. Additionally, thanks to the algorithm's closed-form solution, the optimization can be done in real time, offering the potential for a solution that is adaptive to any variations in physical (e.g., coil separation, Rx rotation, etc.) and/or electrical (e.g., Q-factor, media conductivity, etc.) properties of the link, conditional to a low-power circuit implementation for its evaluation. The efficacy and precision of the solution obtained from the presented analytical model is confirmed with CAD-based simulation results, and later validated using experimental measurements. Our experimental results for two links with different characteristics (resonance frequency, coils size and separation, etc.) show a 52.5% and 67.5% improvement in overall energy storage efficiency compared to the standard CM receiver design in which resonance-to-charging switching is performed when the receiver's LC tank energy accumulation starts to saturate. This is while the presented method does not require any calibration and is designed to be employed by any generic current-mode receiver.

Ionic liquid-based novel polymer electrolytes: electrical and thermal properties

New polymer electrolytes have been prepared from room temperature ionic liquid (IL) and poly(vinylidene fluoride)-hexafluoropropylene copolymer [PVdF-HFP]. The variation of thermal and electrical properties with varying polymer to IL concentration was investigated. The electrolytes had high thermal stabilities. The IL-PVdF-HFP electrolytes were freestanding, flexible films with room temperature conductivities of the order of 10−3 S cm−1. Increase in conductivity was found with increasing IL and also with increasing temperature. Increase in conductivity can be attributed to the fact that with increasing IL amorphicity increases as evident from XRD result. Dielectric studies showed decrease in relaxation time with increasing IL concentration indicating increase in polymer segmental motion which result in increase in conductivity.

Label-Free and Simultaneous Mechanical and Electrical Characterization of Single Plant Cells Using Microfluidic Impedance Flow Cytometry.

Despite that single-cell-type-level analyses have been extensively conducted on animal models to gain new insights into complex biological processes; the unique biological and physiological properties of plant cells have not been widely studied at single-cell resolution. In this work, an electrical impedance flow cytometry was fabricated based on microfluidics with constriction microchannel to simultaneously characterize the mechanical and electrical properties of single plant cells. Protoplasts from two model plant species, the herbaceous Arabidopsis thaliana and the woody Populus trichocarpa, could be readily discriminated by their respective mechanical traits, but not by electrical impedance. On the contrary, overexpression of a red fluorescent protein on plasma membrane resulted in changes in cell electrical impedance instead of cell deformability. During primary cell wall (PCW) regeneration, this extracellular layer outside of protoplasts introduced dramatic variations in both mechanical and electrical properties of single plant cells. Furthermore, the effects of auxin, an essential phytohormone regulating PCW reformation, were validated on this platform. Taken together, our results revealed a novel application of microfluidic impedance flow cytometry in the field of plant science to simultaneously characterize dual biophysical properties at single-cell resolution, which could be further developed as a powerful and reliable tool for plant cell phenotyping and cell fate specification.