Determining Particle Size and Position in a Coplanar Electrode Setup Using Measured Opacity for Microfluidic Cytometry

Microfluidic impedance flow cytometers enable high-throughput, non-invasive, and label-free detection of single-cells. Cytometers with coplanar electrodes are easy and cheap to fabricate, but are sensitive to positional differences of passing particles, owing to the inhomogeneous electric field. We present a novel particle height compensation method, which employs the dependence of measured electrical opacity on particle height. The measured electrical opacity correlates with the particle height as a result of the constant electrical double layer series capacitance of the electrodes. As an alternative to existing compensation methods, we use only two coplanar electrodes and multi-frequency analysis to determine the particle size of a mixture of 5, 6, and 7 µm polystyrene beads with an accuracy (CV) of 5.8%, 4.0%, and 2.9%, respectively. Additionally, we can predict the bead height with an accuracy of 1.5 µm (8% of channel height) using the measured opacity and we demonstrate its application in flow cytometry with yeast. The use of only two electrodes is of special interest for simplified, easy-to-use chips with a minimum amount of instrumentation and of limited size.

Coplanar Capacitive Sensing as a New Electromagnetic Technique for Non-Destructive Evaluation

Coplanar capacitive technique is a relatively novel electro-magnetic Non-Destructive Testing (NDT) method that could be applied to the evaluation of materials by moving a set of electrodes on the surface of the specimen. In addition to the design-related parameters such as electrode shape, size, and the separation distance between the main electrodes, the material of the specimen affects the coplanar capacitive probe performance. In this paper, a 3D Finite Element Modeling (FEM) was employed to assess and identify the electric field behaviour as a function of material under test for non-conducting and conducting specimens with/without defect. Physical experiments were carried out by a pair of rectangular coplanar electrodes on an aluminium specimen with surface defects covered by a 5 mm thick plexiglass insulation layer to verify the simulation results and evaluate the performance of the probe. A good qualitative agreement was observed between the numerical simulations and experimental results.

DEVELOPMENT SHAFT RUN-OUT MEASUREMENT TRANSDUCERS FOR POWERFUL GENERATORS FAULT CONTROL SYSTEM WITH CAPACITIVE COPLANAR CONCENTRIC SENSOR

The paper presents the results of the study of a capacitive radial beating sensor, consisting of a primary transducer with concentric coplanar electrodes and a secondary measuring transducer «capacitance - voltage». The design and results of calculations of the capacitive sensor conversion function presented. The parameters of the circuit of the secondary measuring transducer based on the frequency-independent measuring circuit are determined. The optimal frequency range for measurements selected.

Breakdown Behavior of GaAs PCSS with a Backside-Light-Triggered Coplanar Electrode Structure

The competitive relationship between the surface flashover of the coplanar electrodes and the body current channel was investigated. Breakdown behavior of GaAs photo-conductive semiconductor switch (PCSS) with a backside-light-receiving coplanar electrode structure was studied in this paper. GaAs PCSS was triggered by the laser pulse with an extrinsic absorption wavelength of 1064 nm. Special insulating construction was designed for GaAs PCSS, while the surface of the electrodes was encapsulated with transparent insulating adhesive. Our first set of experiments was at a bias voltage of 8 kV, and the surface flashover breakdown of GaAs PCSS was observed with 10 Hz triggering laser pulse. In the second experiment, at a bias voltage of 6 kV, the body current channel breakdown appeared on the backside of the GaAs PCSS. Compared with these results, the existence of a competitive relationship between the surface flashover breakdown and the body current channel breakdown of the GaAs PCSS was confirmed. When the bias voltage is set within a certain range (just reaching avalanche mode), GaAs PCSS with a backside-light-receiving coplanar electrode structure will undergo the body current channel breakdown. This finding is also consistent with the simulation results.

Three-phase electric power driven electoluminescent devices

Current power supply networks across the world are mostly based on three-phase electrical systems as an efficient and economical way for generation, transmission and distribution of electricity. Now, many electrically driven devices are relying on direct current or single-phase alternating current power supply that complicates utilization of three-phase power supply by requiring additional elements and costly switching mechanisms in the circuits. For example, light-emitting devices, which are now widely used for displays, solid-state lighting etc. typically operate with direct current power sources, although single-phase alternating current driven light-emitting devices have also gained significant attention in the recent years. Yet, light-emitting devices directly driven by a three-phase electric power has never been reported before. Benefiting from our precious work on coplanar electrodes structured light-emitting devices, in this article we demonstrate proof of a concept that light-emitting components can be driven by three-phase electric power without utilizing intricate back-end circuits and can compose state detection sensors and pixel units in a single device inspiring from three primary colors. Here we report a three-phase electric power driven electroluminescent devices fabricated featuring of flexibility and multi-functions. The design consists of three coplanar electrodes with dielectric layer(s) and light emission layer(s) coated on a top of input electrodes. It does not require transparent electrodes for electrical input and the light emission occurs when the top light-emitting layers are connected through a polar bridge. We demonstrate some applications of our three-phase electric power driven electroluminescent devices to realize pixel units, interactive rewritable displays and optical-output sensors. Furthermore, we also demonstrate the applicability of three-phase electrical power source to drive organic light-emitting devices with red, green and blue-emitting pixels and have shown high luminance (up to 6601 cd/m2) and current efficiency (up to 16.2 cd/A) from fabricated three-phase organic light-emitting devices. This novel geometry and driving method for electroluminescent devices is scalable and can be utilized even in a wider range of other types of light-emitting devices and special units.

AC/DC Fields Demodulation Methods of Resonant Electric Field Microsensor

Electric field microsensors have the advantages of a small size, a low power consumption, of avoiding wear, and of measuring both direct-current (DC) and alternating-current (AC) fields, which are especially suited to applications in power systems. However, previous reports were chiefly concerned with proposing new structures or improving the resolution, and there are no systematic studies on the signal characteristics of the microsensor output and the demodulation methods under different electric fields. In this paper, the use of an improved resonant microsensor with coplanar electrodes, and the signal characteristics under a DC field, power frequency field, and AC/DC hybrid fields were thoroughly analyzed respectively, and matching demodulation methods derived from synchronous detection were proposed. We theoretically obtained that the frequencies of the detectable electric fields should be less than half of the resonant frequency of the microsensor, and that the sensitivities of the microsensor were identical for AC/DC hybrid fields with different frequencies. Experiments were conducted to verify the proposed demodulation methods. Within electric field ranges of 0–667 kV/m, the uncertainties were 2.4% and 1.5% for the most common DC and 50 Hz power frequency fields, respectively. The frequency characteristic test results of the microsensor were in agreement with those of the theoretical analysis in the range of 0–1 kHz.

Use of an Insulation Layer on the Connection Tracks of a Biosensor with Coplanar Electrodes to Increase the Normalized Impedance Variation

New technologies, such as biosensors and lab-on-a-chip, are reducing time consumption and costs for the detection and characterization of biological cells. One challenge is to detect and characterize cells and bacteria one by one or at a very low concentration. In this case, measurements have very low variations that can be difficult to detect. In this article, the use of an insulation layer on the connection tracks of a biosensor with coplanar electrodes is proposed to improve a biosensor previously developed. The impedance spectroscopy technique was used to analyze the influence of the insulation layer on the cutoff frequencies and on the normalized impedance variation. This solution does not induce changes in the cutoff frequencies, though it permits improving the normalized impedance variations, compared to the same biosensor without the insulation layer.