High Dielectric Constant Of Water Research Articles

System for automatically regulating the supply of nitrogen traps : ( U.S.S.R.) B. A. Ivanov, Instrum. & Exper. Tech., 1, (Oct. 1963, 182–183). (Transl. from Pribory i Tekh. Eksp., 1, Jan.–Feb., 1963.)

In this work, we report a unique on-chip approach of cancelling feedthrough applied to a Thin-film Piezoelectric-on-Silicon (TPoS) MEMS resonator fully immersed in deionized (DI) water to enhance the signal-to-background ratio (SBR) in the context of full electrical characterization. We experimentally validate the proposed technique by demonstrating an SBR as high as 25dB despite a reasonably low quality factor (Q) of 162 and high dielectric constant of water from a reference SBR of 3.45dB. The proposed technique employs a pair of differential inputs where one input actuates the device while the other input cancels feedthrough and targets package-level parasitic elements associated with measuring in water. The resulting net feedthrough capacitance is reduced from 185fF to just 2.04fF in DI water. These results are based on a simple practical setup where the fabricated device is interfaced with a customized printed circuit board (PCB) by wire-bonds.

Capacitance Hygroscopy and some of its Applications

BEING myself concerned with the properties of both soil and cotton, I read with particular attention the article on this subject by Dr. Lawrence Balls in NATURE of December 17. I have found it difficult to decide exactly how Dr. Balls considers the moisture content of the soil or cotton bale under test affects his condenser reading. From his opening paragraph one might conclude that he believes the dielectric property of water to be the dominant factor. Later, however, he remarks that “variations of resistance in the unknown capacity can also alter the ‘capacitance’ readings”. An instrument which responds to changes in electrical resistance is influenced by the salt as much as by the moisture content. One responding to the high dielectric constant of water contained in a material would, on the other hand, be most valuable. There are some who might easily be misled into thinking that a dielectric constant is involved merely because condensers are used in the measurement. In view of the statement I have quoted, it appears that Dr. Balls is aware that his apparatus measures the equivalent parallel capacity of the system tested.

Capacitance Hygroscopy and some of its Applications

SOME experiments were briefly noted in this journal last April1 whereby the high dielectric constant of water was used to indicate variations in the water-content of substances contiguous to a leaky condenser, by means of a resonance method. It would seem that other workers are exploring the same track, with the difference that they draw samples which are placed in special condenser-containers for measurement, whereas I prefer to take full advantage of the method in evading the ubiquitous ‘sampling-error’ so far as possible; even at the sacrifice of some accuracy in the actual determination. Great accuracy is probably unobtainable in any case; the dielectric constant even of free water is not a constant, but the margin of difference between water around 80 and most other common substances below 8 is large enough for most classes of comparative work.

Film Characteristics of Electrolytic Condensers

Electrolytic condensers of the film-forming type have some interesting characteristics which have never been satisfactorily explained. Extremely thin oxide or hydroxide films formed on the surface of the metal anodes seem insufficient in themselves to explain the complete action. Likewise, an electromotive equilibrium is insufficient to explain the action. A résumé of former research reveals a great deal of information of large practical value in building electrolytic condensers but little of value from a theoretical standpoint. Reviewing the prominent papers, it appears that aluminum has been the chief subject of discussion for condenser anodes. Such anodes show small leakage currents in selected electrolytes at low temperatures. Increasing voltage, temperature, or electrolyte concentration cause increases in leakage; the addition of impurities also has a deleterious effect. The oxide-gas theory of rectification as applied to electrolytic condensers by Guntherschulze predicts changes in capacity for variations in pressure. Experiments do not substantiate the presence of gas. The oxide layer alone is unable to fulfil the necessary conditions found. Electrolytic condensers with extremely low applied voltages show large variations in measured capacity from high-voltage measurements. The results indicate a film in which ion penetration plays a large part. The presence of a film saturated with water as the dielectric overcomes a number of former obstacles, and lessens the necessity for the very thin films formerly assumed, due to the high dielectric constant of water.

Rapid Estimation of Water-Content in Undisturbed Soil and in Bales of Cotton

AN instantaneous method for estimating the moisture content of soil, at any particular spot below the surface of the ground, even approximately, should be very useful in plant physiology, irrigation, and in soil science generally. The high dielectric constant of water suggested to me that the variations in capacity of a ‘leaky’ condenser permanently buried in the soil should serve this purpose.