Diaphragm Electrode Research Articles

Final analysis of the pilot trial of diaphragm pacing in amyotrophic lateral sclerosis with long-term follow-up: diaphragm pacing positively affects diaphragm respiration

BackgroundRespiratory insufficiency is the major cause of mortality in patients with amyotrophic lateral sclerosis or Lou Gehrig’s disease. This is the final report of the diaphragm pacing (DP) pilot trial. MethodsPatients underwent laparoscopic diaphragm electrode implantations and subsequent conditioning of diaphragms. Serial respiratory function tests were performed in the initial year and followed until death. ResultsSixteen patients were implanted with no perioperative or unanticipated device-related adverse events. There were 452 implant-months of follow-up. DP allowed greater movement of the diaphragm under fluoroscopy, increased muscle thickness, and decreased the decline in forced vital capacity. Median survival from implant was 19.7 months with the cause of death respiratory in only 31%. ConclusionsLong-term analysis of DP in amyotrophic lateral sclerosis showed no safety issues and can positively influence diaphragm physiology and survival. This formed the initial basis for subsequent US Food and Drug Administration approval.

Simulation of Low Pressure MEMS Sensor for Biomedical Application

Micromachining technology has greatly benefited from the success of developments in implantable biomedical microdevices. In this paper, microelectromechanical systems (MEMS) capacitive pressure sensor operating for biomedical applications in the range of 20–400 mm Hg was designed. Employing the microelectromechanical systems technology, high sensor sensitivities and resolutions have been achieved. Capacitive sensing uses the diaphragm deformation-induced capacitance change. The sensor composed of a rectangular polysilicon diaphragm that deflects due to pressure applied over it. Applied pressure deflects the 2 µm diaphragm changing the capacitance between the polysilicon diaphragm and gold flat electrode deposited on a glass Pyrex substrate. The MEMS capacitive pressure sensor achieves good linearity and large operating pressure range. The static and thermo electromechanical analysis were performed. The finite element analysis data results were generated. The capacitive response of the sensor performed as expected according to the relationship of the spacing of the plates.

Electrode diaphragm electrode assembly for alkaline water electrolysers

The cast macroporous Zirfon ® diaphragm has been developed many years ago to be used as a gas separator in industrial alkaline water electrolysers. It has also been proven as an excellent separator in alkaline electrolysers for space applications. For space applications it is preferred to operate the electrolyser with a fixed alkaline electrolyte so that no pumps are needed and all kinds of electrolyte circulation problems can be avoided. The target of this development was the casting of an Electrode Diaphragm Electrode (EDE) as a single unit comprising the anode, the diaphragm and the cathode. This EDE should operate at a minimum cell voltage and the highest possible gas purity.

Analytical modeling of electrostatic membrane actuator for micro pumps

A large class of micro pumps consists of a cavity in a substrate, a diaphragm that seals the cavity, and inlets and outlets for the cavity which are controlled by valves. The cavity is initially filled with a fluid. The diaphragm is then actuated by a voltage between the diaphragm and the cavity door to compress the fluid. When the pressure exceeds a certain value, the fluid is expelled. During actuation, the electrostatic attractive force of the substrate and the pressure rise in the fluid lead to the bending and stretching of the diaphragm. Thus, the prediction of the pump performance (e.g., fluid pressure, diaphragm stresses) requires the solution of a coupled nonlinear elasto-electro-hydrodynamic problem. In this paper, a simplified analytical model is developed to predict the state of an electrostatically actuated micro pump at equilibrium. The state includes the deformed shape and the internal stresses of the diaphragm and the pressure of the fluid when the actuator is subjected to a given applied dc voltage. The model is based on the minimization of the total energy consisting of the capacitive energy, the strain energy of the diaphragm, and the energy of the fluid which is considered to be an ideal gas. The method is employed to study two pumps, one with an axisymmetric single cavity, and the other with an axisymmetric annular cavity (a cavity with an island in the middle). In the former case, upon actuation, the diaphragm contacts the cavity door from the outer periphery. Thus, energy is a function of the radius of the contact front, and equilibrium configuration is achieved at a radius where the derivative of the energy with respect to the radius vanishes. In the latter case, upon actuation, the diaphragm contacts the cavity from both of the inner and the outer peripheries. Here, equilibrium is reached when the derivatives of the energy with respect to the radii of both of the inner and outer periphery contact points vanish. It is expected that most practical pumps can be analyzed by one of the two formulations presented in the paper. Our analyses of both pumps indicate that the pressure of the gas at equilibrium increases only slightly when the stiffness of the diaphragm is increased, whereas it changes nearly inversely with the thickness of the dielectric between the diaphragm electrode and the cavity floor. Also, as expected, the pressure increases as the initial volume of the cavity (i.e., the volume of the gas to be compressed) is decreased. Furthermore, we find that the calculated stresses in the diaphragm do not exceed the typical yield stress values of many glassy polymers, a candidate material for the diaphragm. Therefore, the assumption of a linear elastic diaphragm employed in the proposed model does not put a limitation on the predictions. Dielectric breakdown may be a limiting factor for the maximum attainable pressure rather than the mechanical strength of the diaphragm material. Although stresses are low, they may be severe enough to cause delamination between different layers in the diaphragm, too.

Potentiometric determination of tanatalum with a hexafluorotantalate(V) -selective liquid membrane electrode

Brilliant Green-hexafluorotantalate(V) extract in nitrobenzene was used as electroactive material to prepare a hexafluorotantalate(V) -selective liquid membrane electrode with a PVC support. The electrode body was made from concentric polypropylene tubes which were joined by a cork. The liquid membrane electrode was connected with fluoride-selective electrode as internal reference and ground glass diaphragm ( Ag AgCl ) electrode as external reference electrode to obtain a complete cell assembly for the potential measurements. The concentrations of sulphuric and hydrofluoric acid, for the optimum response of the electrode to hexafluorotantalate(V), were found to be 1 M each in the test solutions. The electrode was found to respond to hexafluorotantalate(V) in the concentration range of 2.0 × 10 −6−1.0 × 10 −2 M tantalum(V) with a slope of − 59 mV per decade and detection limit of 3.7 × 10 −7 M tantalum(V) within 20–120 s. The effects of forty diverse ions on the electrode response to the hexafluorotantalate(V) have been studied and the electrode has been found to be highly selective to hexafluorotantalate(V). The newly developed liquid membrane electrode has been applied successfully to the determination of tantalum in tantalite-columbite ores by direct, sample addition, standard addition, and Gran's plot potentiometric techniques.

Electrocatalytic Oxidation of Alcohol at a Polypyrrole Diaphragm Electrode Coated with Diaphorase and Alcohol Dehydrogenase

Electrocatalytic Oxidation of Alcohol at a Polypyrrole Diaphragm Electrode Coated with Diaphorase and Alcohol Dehydrogenase

Diaphragm for use in condenser microphone type detector

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Kinetic study of the rest potential on a platinum|oxygen diaphragm electrode

Kinetic study of the rest potential on a platinum|oxygen diaphragm electrode

Hydrogen Permeation Studies: II . Vanadium as a Hydrogen Electrode in a Lithium Hydride Cell

Hydrogen permeation of pure vanadium has been investigated over the temperature range of 450°–550°C and 1 atm hydrogen pressure. An activation energy of has been determined. A lithium hydride cell using a vanadium diaphragm electrode has been operated for a period of 540 hr. Current densities obtained during operation were 180 ma/cm2 at one‐half open‐circuit voltage.