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MEMS Fabrication
Published in Mohamed Gad-el-Hak, MEMS, 2005
Putting detection and signal conditioning circuits right next to the sensing element enhances the performance of the sensing system, especially when dealing with high-impedance sensors. A key benefit of surface micromachining, besides small device size and single-sided wafer processing, is its compatibility with CMOS processing. IC compatibility implies simplicity and economy of manufacturing. In the examples at the end of this chapter, we will discuss how Analog Devices used a mature 4-μm BICMOS process to integrate electronics with a surface micromachined accelerometer.
Development of a Compact Electrical Impedance Measurement Circuit for Protein Detection Two-electrode Impedance Micro-sensor
Published in IETE Journal of Research, 2023
Tuan Vu Quoc, Viet Nguyen Ngoc, Bao-Anh Hoang, Chun-Ping Jen, Trinh Chu Duc, Tung Thanh Bui
The LIA requires a very high-accuracy 90° phase shift module that works in the frequency range from 10 to 200 kHz. To achieve two signals with phase of 0 and 90°, the oscillators utilize a dual AD 9850 IC working with a synchronized clock. The frequency and phase of the two signals are set simultaneously to achieve a precisely phase shifting between the two signals. Time-division multiplexing is used in this design with these different phases shifted two signals U0 and U90. The measurement gathers data of U0 and U90 output voltages. The frequency of the two signals with 0 and 90° phase shifted then will be changed gradually to supply the exciting signal and reference signal to the biosensor and LIA. In the conditioning circuit, the auto-balance bridge circuit is used to convert impedance to output voltage. The conditioning circuit consists of an operation amplifier, which can work at high frequency and high impedance measurement, and the reference resistor R0 to convert current to voltage.
Natural convection mass transfer correlation of the electropolishing of horizontal cylinders with active ends
Published in Transactions of the IMF, 2021
M. A. El-Naggar, M. H. Abdel-Aziz, G. H. Sedahmed
In another series of experiments hollow cylinders (tubes) (without active ends) of similar dimensions were used as anodes. The electrical circuit consisted of a 10-volt direct current power supply with a voltage regulator, and a digital ammeter connected in series with the cell. Polarisation curves from which the limiting current was determined were plotted by increasing the current stepwise and measuring the corresponding steady-state anode potential against a reference copper electrode placed in the cup of a Luggin tube filled with the cell solution. A high impedance digital voltmeter was used to measure the anode potential. The tip of the Luggin tube was placed 0.5–1 mm from the anode surface.15 Before each run the anode was etched with 5% HCl for 5 min to remove oxides then washed in distilled water and dried. The anode was placed in the centre of the solution midway between the top and bottom of the solution. Three different concentrations of H3PO4 were used namely 8, 10, and 12 M, all solutions were prepared using AR H3PO4 and distilled water. The temperature was 22±1°C during experiments. The physical properties of the system used in data correlation was taken from the literature.13Table 1 shows the effect of H3PO4 concentrations on these properties (ρ, µ, D and Cs).
Topological neural network of combined AE and EN signals for assessment of SCC damage
Published in Nondestructive Testing and Evaluation, 2020
Luigi Calabrese, Massimiliano Galeano, Edoardo Proverbio, Domenico Di Pietro, Angelo Donato
In an independent way, the EN recording was performed using a three electrodes set-up. To obtain this configuration, inside the SCC cell were applied two additional electrodes realised with the same material of the SCC specimen and the same surface area, for current and potential EN measurements, respectively. The SCC sample was used as a working electrode in order to allow recording of combined electrochemical and mechanical induced phenomena. Signals were recorded by means a PAR Versastat 4 potentiostat, using a zero resistance ammeter configuration for the current signal, while the potential signal was acquired by a high impedance voltmeter (1 Tera Ohm). Acquisition frequency was imposed to 1 Hz. A description of the EN variables calculated from current and voltage records is reported in [12].