Abstract: A measuring instrument for detecting a fill level or a limit level of a medium, for example fill levels in containers or chambers, is provided. The measuring instrument includes a sensor unit, which takes at least two measurements at two different penetration depths in the medium. For this purpose, an arithmetic-logic unit makes calculations so as to distinguish complete covering of the sensor unit by a medium from adhesion of parts of the medium to the sensor unit, using the results of the measurements.

Abstract: In the present invention, the solid contacted ISE and the solid contacted reference are based on a conductive porous network with a solid contact and membrane disposed thereon. The porous networks are not only mechanically stable, but also provide pore structure for the solid contact and membrane to intercalate, which enhances the life time and stability of the sensors. The invention further incorporates a unique fluidic fitting sensor and sealing mechanism so that measurements can be taken at high pressures. The fitting design has many benefits, such as low cost and disposability, which allows them to be mass manufactured. These sensors can be produced for detection of many different kinds of ions by applying different types of ion selective membranes, including polyvinylchloride (PVC) based ion-selective membranes and fluorous matrixes based ion-selective membranes.

Abstract: A method for measuring and/or calibrating a gas sensor for determining oxygenic gas components in gas mixtures in exhaust gases of internal combustion engines. The gas sensor has one internal pump electrode IPE, one external pump electrode APE and one decomposition electrode NOE. The measurement and/or calibration may be carried out during the ongoing operation of the gas sensor by removing the gas component and/or oxygen from one of the chambers, by introducing oxygen in a controlled manner into one of the chambers with the aid of electrochemical pumping processes. The changes caused by the introduced oxygen are measured against an additional electrode and the gas sensor may be measured and/or calibrated using the measured values.

Abstract: An auto-calibration system for diagnostic test strips is described for presenting data individually carried on each test strip readable by a diagnostic meter. The carried data may include an embedded code relating to data particular to that individual strip. The data is presented so as to be read by a meter associated with the diagnostic test strip in order to avoid manually inputting the information.

Abstract: The present invention relates to the development of a biosensor to determine potassium in human blood serum using dibenzo-18-crown-6 (DB18C6) as ionophore. Human blood serum contains potassium in ppm levels i.e 137 to 200 mg/litre and sodium co exists with a 30 times higher concentration. Such a high concentration tends to interfere the selectivity towards potassium, but DB18C6 proves to have an excellent selectivity towards potassium and is highly sensitive to the lowest concentration of potassium levels present in the human blood serum. So the present invention reports the fabrication and characterization of ISFET (Ion Selective Field Effect transistor) coated with a monolayer of crown ether, dissolved in chloroform, on the gate of electrode.

Abstract: A method of addressing and driving an electrode array includes the step of addressing one or more electrodes within the array using a plurality of row and column lines. In one aspect of the method, a value corresponding to a voltage is stored in a local memory associated with each electrode. The addressed electrodes are then driven at the voltages corresponding to the stored values. In another aspect of the method, a driving element associated with each addressed electrode is selectively coupled with a voltage line so as to charge the electrode with the voltage on the voltage line. The device and methods may be used in the synthesis of biopolymers such as oligonucleotides and peptides.

Abstract: An addressable biologic electrode array includes an array of electrodes disposed on a support, the array of electrodes being selectively addressed and driven using a memory associated with each electrode of the array, the driven electrodes being driven at one of a plurality of stimulus levels by a source of electrical current or voltage external to the array.

Abstract: A biologic electrode array is formed on a semiconductor substrate. A matrix of electrode sites is disposed on the semiconductor substrate. A matrix of optical detectors is disposed beneath the electrode sites in the semiconductor substrate, wherein each electrode site is associated with a corresponding optical detector. The optical detectors are coupled to detection circuitry formed on the semiconductor substrate. The electrode sites may include slitted electrodes, punctuated electrodes, or optically transparent electrodes.

Abstract: A method of addressing and driving an electrode array includes the step of addressing one or more electrodes within the array using a plurality of row and column lines. In one aspect of the method, a value corresponding to a voltage is stored in a local memory associated with each electrode. The addressed electrodes are then driven at the voltages corresponding to the stored values. In another aspect of the method, a driving element associated with each addressed electrode is selectively coupled with a voltage line so as to charge the electrode with the voltage on the voltage line. The device and methods may be used in the synthesis of biopolymers such as oligonucleotides and peptides.

Abstract: A biologic electrode array assembly is formed on an integrated circuit chip that includes an array of electrodes. At least one metal oxide semiconductor (MOS) switch is coupled to at least one of the electrodes within the array. A voltage line is provided that is selectively connected to the at least one electrode via the MOS switch. A voltage source is coupled to the voltage line. In one preferred aspect of the invention, the MOS switch is a CMOS switch. In another aspect of the invention, an addressable memory is associated with the at least one electrode located within the array.

Abstract: A system and method for reducing the number of input/output connections required to connect a microfluidic substrate to an external controller for controlling the substrate. In one example, a microfluidic processing device is fabricated on a substrate having a plurality of N independently controllable components, (e.g., a resistive heating elements) each having at least two terminals. The substrate includes a plurality of input/output contacts for connecting the substrate to an external controller, and a plurality of leads for connecting the contacts to the terminals of the components. The leads are arranged to allow the external controller to supply control signals to the terminals of the components via the contacts using substantially fewer contacts than the total number of component terminals.

Abstract: An ultramicroelectrode is disclosed which includes a) a silicon substrate; b) a silicon oxide insulating layer; c) a titanium adhesion layer; d) an iridium layer; e) a gold bond pad layer; f) a titanium adhesion layer; and g) a silicon dioxide insulating layer. In a preferred embodiment, the f) and g) layers have been partially or totally removed. Preferably, the ultramicroelectrode of the invention does not include mercury.

Abstract: An electroanalytical apparatus defining a Static Mercury Drop Electrode cell which includes a capillary tube at the end of which is formed mercury drops to constitute the working electrode including a container for continuously receiving and collecting mercury that has formed said working electrode and has become contaminated, a purifying vessel positioned in fixed relationship to the capillary tube, conduit means for continuously transferring mercury into the purifying vessel from the container, means for introducing highly oxygenated water into the purifying vessel at a location above the mercury collected in the vessel such that surface contact is established between said highly oxygenated water and the mercury collected in the purifying vessel, and means for continuously drawing mercury from the purifying vessel and feeding it as purified mercury to the capillary tube.

Abstract: A biologic electrode array is formed on a semiconductor substrate. A matrix of electrode sites is disposed on the semiconductor substrate. A matrix of optical detectors is disposed beneath the electrode sites in the semiconductor substrate, wherein each electrode site is associated with a corresponding optical detector. The optical detectors are coupled to detection circuitry formed on the semiconductor substrate. The electrode sites may include slitted electrodes, punctuated electrodes, or optically transparent electrodes.

Abstract: A method of addressing and driving an electrode array includes the step of addressing one or more electrodes within the array using a plurality of row and column lines. In one aspect of the method, a value corresponding to a voltage is stored in a local memory associated with each electrode. The addressed electrodes are then driven at the voltages corresponding to the stored values. In another aspect of the method, a driving element associated with each addressed electrode is selectively coupled with a voltage line so as to charge the electrode with the voltage on the voltage line. The device and methods may be used in the synthesis of biopolymers such as oligonucleotides and peptides.

Abstract: An improved biologic electrode array and methods for manufacturing and using the same. In one aspect, a matrix of electrodes each coupled to a respective sample-and-hold circuit is provided. The electrodes and sample-and-hold circuits are integral and form an array within a single semiconductor chip, such that each sample-and-hold circuit may be loaded with a predefined voltage provided by a single, time-shared digital-to-analog converter (DAC). Further, all of the sample-and-hold circuits may be accessed through a multiplexer which may be scanned through some or all of the electrode locations. Each sample-and-hold circuit may comprise a capacitor and one or more transistor switches, the switch(es), when closed, providing electrical communication between the capacitor and a source line formed in the matrix.

Abstract: An acidity measuring apparatus includes a measuring container for accommodating an electrolyte solution including one of a 1,2-benzoquinone derivative and a 1,4-benzoquinone derivative, an organic solvent, an electrolyte and an acid-containing subject for measurement; a working electrode, a counter electrode and a reference electrode section provided in the measuring container and immersed in the electrolyte solution; and a control section for sweeping a potential of the working electrode within a prescribed range and for detecting a value of a pre-peak current generated by the acid and flowing between the working electrode and the counter electrode.

Abstract: An electroanalytical voltammetric cell containing:(a) a cell body housing a counter electrode and a working electrode;(b) means for causing a sample solution to flow through the cell and to fill a space between the counter-electrode and the working electrode; and(c) a vibrator present in the space between the two electrodes which vibrates in order to fully mix the sample solution in the space.

Abstract: The present invention provides microband electrode array sensors for detecting the presence and measuring the concentration of analytes in a sample. The microband electrodes of the invention have both a width and a thickness of microscopic dimensions. Preferably the width and thickness of the microband electrodes are less than the diffusion length of the analyte(s) of interest. In general, both the thickness and width of the electrodes are less than about 25 micrometers. The electrodes are separated by a gap insulating material that is large enough that the diffusion layers of the electrodes do not overlap such that there is no interference and the currents at the electrodes are additive. Microband electrode arrays of this invention exhibit true steady-state amperometric behavior.

Abstract: The electroanalytical, voltammetric cell includes a cell body housing, in addition to a reference electrode, a working electrode and, in its lowermost portion, a counter-electrode. An arrangement for deoxygenating the sample solution includes feeding the sample solution through a deoxygenation conduit in contact with a stream of an inert gas. An inlet for the deoxygenated sample solution is provided in the cell body in the space between the working electrode and the counter-electrode, and an exit for the sample solution is provided in the cell body at a level above the working electrode. Vacuum and/or pressure is utilized for causing the sample solution to flow to the exit, to be discharged from the cell above the working electrode, thus assuring that the space between the working electrode and the counter-electrode is constantly filled with sample solution.

Abstract: Two types of HgO-modified electrodes are disclosed. The HgO-modified electrode according to the present invention comprises, HgO particles as precursor of mercury, which can be exposed on the surface of the said electrode and then can be reduced electrochemically into micro-droplets of mercury; and electro-conductive material to maintain optimal conductivity of the said modified electrode. In the HgO-modified electrode according to the present invention, built-in mercury precursor, HgO can be utilized feasibly for the generation of the surface mercury droplets by in situ electrochemical treatment or pretreatment without necessity of Hg.sup.2+ solution. The electrode surface can be renewed easily either by a simple polishing process for the bulk-modified electrode type-I or by simple exchange for the screen-printed disposable type modified electrode type-II. So further simplification of anodic stripping analysis process is possible by employing the HgO-modified electrodes according to the present invention.

Abstract: Ion-selective membranes are disclosed which are suitable for use in ion-selective sensors. The membranes include a mercuracarborand ionophore. Exemplary ion-selective membranes include Mercuracarborand-3 as the ionophore which is incorporated within a polymer matrix. The ion-selective membranes may be used in a wide variety of ion sensors including ion-selective membrane electrodes.

Abstract: An improved biologic electrode array and methods for manufacturing and using the same. In one aspect, a matrix of electrodes each coupled to a respective sample-and-hold circuit is provided. The electrodes and sample-and-hold circuits are integral and form an array within a single semiconductor chip, such that each sample-and-hold circuit may be loaded with a predefined voltage provided by a single, timeshared digital-to-analog converter (DAC). Further, all of the sample-and-hold circuits may be accessed through a multiplexer which may be scanned through some or all of the electrode locations. Each sample-and-hold circuit may comprise a capacitor and one or more transistor switches, the switch(es), when closed, providing electrical communication between the capacitor and a source line formed in the matrix.

Abstract: A microsensor for electrochemical measurements allowing the determination of concentration or concentration profile of at least one chemical compound with small size or molecular weight, under organic, inorganic, neutral or ionic form in an aqueous environment. The microsensor comprises an array (15) of microelectrodes (16), assembled on a chip (10) supported by an isolating substrate (7), and linked with at least one conductor protected by an insulating layer to a contact allowing the connection to a measuring apparatus. The said microsensor is totally coated with an hydrophilic gel (25) which is chemically inert with respect to the chemical compound, is hydrated at a level of at least 70 %, and has a thickness superior to 10 times the size of the microelectrodes (16). And an integrated electrochemical microsystem including the microsensor.

Abstract: Composition, comprising in homogeneous distribution A) at least one salt containing a lipophilic anion, B) a plasticiser-free thermoplastic randomly segmented polyurethane which is soluble in organic solvents, a polyurea or a polyurethane urea, which components are formed from a) 5-45% by weight of an aromatic, cycloaliphatic or linear aliphatic dilsocyanate, b) 0-20% by weight of a linear or branched C2-C12alkylenediol or C2-C12alkylenediamine, c) 0-75% by weight of a polytetrahydrofuran or aminopropyl-terminated polytetrahydrofuran, d) 0-10% by weight of a polyethylene glycol or aminopropyl-terminated polyethylene glycol, e) 0-75% by weight of a polypropylene glycol or aminopropyl-terminated polypropylene glycol, which composition contains f) 15-95% by weight of a hydroxy-, hydroxypropyl- or aminopropyl-terminated polydimethylsiloxane, the percentages relating to the amount of polymer, and the sum of components a) to f) being 100, and C) a nonionic ionophore which forms a complex with Ca++ ions.

Abstract: An efficient method for the microfabrication of electronic devices which have been adapted for the analyses of biologically significant analyte species is described. The techniques of the present invention allow for close control over he dimensional features of the various components and layers established on a suitable substrate. Such control extends to those parts of the devices which incorporate the biological components which enable these devices to function as biological sensors. The materials and methods disclosed herein thus provide an effective means for the mass production of uniform wholly microfabricated biosensors. Various embodiments of the devices themselves are described herein which are especially suited for real time analyses of biological samples in a clinical setting. In particular, the present invention describes assays which can be performed using certain ligand/ligand receptor-based biosensor embodiments.

Abstract: A process is provided for the electrochemical analysis of compounds of solutions, such as can, e.g., be used in chemical analysis or for control measurements in industrial and environmental sectors. Identification or detection of individual substances takes place by the deposition thereof on electrodes and subsequent detection of the deposited substances. In the process, use is made of a plurality of electrodes. The substances to be identified from the solution are so simultaneously deposited on the electrodes that each electrode is coated with a different substance or substance mixture. Then, the deposited substances are simultaneously identified on the individual electrodes. Thus, the measuring time is significantly shortened and the risk of faulty measurements due to interactions between the substances to be identified on the electrodes is significantly reduced.

Abstract: A photo-ablation technique is used to create apertures (4) in a layer (2) of electrically insulating material and allow electrically conducting material (3) exposed through the apertures to create a microelectrode. The microelectrode can be used for assay methods and in an assay unit.

Abstract: An electrochemical sensor for remote detection, particularly useful for metal contaminants and organic or other compounds. The sensor circumvents technical difficulties that previously prevented in-situ remote operations. The microelectrode, connected to a long communications cable, allows convenient measurements of the element or compound at timed and frequent intervals and instrument/sample distances of ten feet to more than 100 feet. The sensor is useful for both downhole groundwater monitoring and in-situ water (e.g., shipboard seawater) analysis.

Abstract: Electrochemical heavy metal analysis includes a printed electrode having a layer of a mercury compound or salt supported thereon. The compound or salt is reduced to metallic mercury in use of the electrode. The mercury layer may comprise a layer of hydroxyethyl cellulose or other permeable polymer.

Abstract: A photo-ablation technique is used to create apertures (4) in a layer (2) of electrically insulating material and allow electrically conducting material (3) exposed through the apertures to create a microelectrode. The microelectrode can be used for assay methods and in an assay unit.

Abstract: A device for batch injection stripping voltammetric analysis of metal traces, of very high sensitivity. This sensitivity extends down to about 0.03 to 0.3 ppb for certain metals. The microanalysis can be carried out at a high rate and in addition to the high sensitivity is characterized by accuracy and high reproducibility. One of the main features is a novel microcell with a rotating working electrode of the mercury coated graphite type.

Abstract: A simple robust sensor probe for determining the magnesium concentration in molten metal alloys in real-time. The probe provides needed process control information in molten metal technologies and has particular application to processes for removing magnesium impurities from scrap aluminum. The probe employs a specially constructed electrochemical concentration cell adapted for repeated immersions into vessels containing molten metal alloys. Specifically, the probe comprises two electrodes, both inert to a molten salt layer, to the molten metal (aluminum), and to magnesium. One electrode comprises an inverted molybdenum cup, a magnesium reference material, and a fibrous ceramic wick, e.g., yttrium oxide, for retaining molten salt therein in contact with the magnesium reference material when the sensor probe is first inserted into the molten salt layer and then into the molten aluminum layer.

Abstract: Screen printing technology is employed in the batch fabrication of the contacts and polymeric membranes of solid-state ion-selective sensors. The process achieves high yield with very reproducible results. Moreover, membrane thickness can easily be predetermined, as it is directly related to the thickness of the screen or stencil. The process of the present invention is compatible with many integrated circuit manufacturing technologies, including CMOS fabrication. Advantageous polymeric membrane paste compositions include a polyurethane/hydroxylated poly(vinyl chloride) compound and a silicone-based compound in appropriate solvent systems to provide screen-printable pastes of the appropriate viscosity and thixotropy.

Abstract: A flow-through cell has a working electrode, an auxiliary electrode, a reference electrode, and a channel. The working electrode is a mercury drop electrode. The channel has a cross-sectional area of less than 1 mm.sup.2 in the region of the working electrode. The mercury drop is situated in the channel.

Abstract: A mercury drop arrangement tests electrochemically a sample solution, in a horizontal or vertical orientation, employing mercury which is delivered from a mercury reservoir to the test solution via a valve and mercury capillary tube. The mercury is valved to deliver one drop of mercury to the end of the capillary tube which is immersed in the sample solution. An electrochemical test of the sample solution can be performed when the mercury drop is in place, and if the mercury drop is not in place, the mercury in the capillary tube forms a microelectrode. The mercury capillary tube can easily be removed for replacement or cleaning when the valve is closed. Closing of the valve produces electrical isolation of the reservoir contents from the mercury in the mercury capillary tube, including the mercury drop itself. Such electrical isolation from the mercury reservoir precludes electrical noise generated in the reservoir from contaminating the voltammetric data.

Abstract: An improved mercury electrode for electrochemical analysis is formed by a small diameter thread of liquid mercury contained within an inert tube which, at one point along its length, has an short, fixed length of thin walled tubular semipermeable membrane surrounding and forming the electrodes' active surface in order to prevent or reduce fouling of the surface while allowing the mercury thread to be advanced through the membrane to expose a fresh active surface whenever desired.

Abstract: An ion-selective reference probe which is adapted for use with potentiomec measurement systems is disclosed. The reference probe is non-chloride based and employs a specially adapted electrolyte which is reversible (i.e. with regard to ionic activity). More particularly, the electrolyte includes appropriate concentrations of ethylenediamine and copper(II) ions in a solvent to permit reversibility of the electrolyte within a desired range. Junction potential between the electrolyte and a test solution is minimized by forming the electrolyte from a portion of the test solution.

Abstract: A metal melt is used as a measuring electrode while a pure form of a particular metal component to be measured or an alloy containing it is used as a standard electrode. The active substance to come in contact with the standard electrode includes at least one halide of an alkali halide and an alkaline earth halide, both having ion conductivity, and a halide of the particular metal component, any one of such halides consisting of a solid phase and a liquid phase. This active substance is provided such that it can come into contact with the metal melt and is used as an electrolyte as well. It is thus possible to provide a continuous detection of the concentration of the particular component in the molten metal to be measured.

Abstract: An electrode assembly for use in quantifying the levels of various metals in an aqueous solution. In one embodiment, the electrode assembly comprises a substrate, the substrate being a silicon chip upon which a layer of silicon dioxide has been grown. A plurality of gold bond pads and gold interconnect traces are deposited by microphotolithography onto the silicon dioxide layer. An array of iridium deposits are then patterned by microphotolithography onto the interconnect traces at predefined locations. A passivation layer is deposited by plasma enhanced chemical vapor deposition over the finished metallization to electrically insulate it from external solutions. Plasma etching is then used to expose at least a portion of each of the iridium deposits. Just prior to analytical use, one or more of the exposed iridium elements are electroplated with mercury. The present invention is also directed to a field deployable sensor including the above-described electrode assembly.

Abstract: A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

Abstract: A miniaturized sensor element comprises a capillary having first and second ends with a channel therebetween. One of the ends is closed while the other is open. Near the closed end, the capillary material which softens when heated, is heated and gas is supplied to the open end. This expands a chamber near the closed end which can be shaped and sized by moving the point of heating and varying the gas supply into the channel. The initially closed end is then opened and the channel inverted. The initially open end is then closed and again the capillary is heated and gas is supplied to form and shape a second chamber in the channel. After this, the closed end of the channel is again opened and both now open ends are smoothed to complete the capillary for use as part of a miniaturized sensor element.

Abstract: Disclosed are a method and apparatus for trace metal testing using mercury-coated screen printed electrodes. Both voltammetric and potentiometric stripping analysis are used. Sample solutions were tested employing both stirring and non-stirring, as well as aeration and deaeration procedures. Microliter samples suitable for slide mounting were also employed.

Abstract: A glass pH electrode which comprises a silver-silver bromide inner electrode and an electrode solution for the inner electrode which is a zwitterionic buffer solution.

Abstract: A zirconia oxygen sensor for measuring oxygen potential in the molten bath of a metal or alloy having a melting point of 350-550.degree. C., which comprises a reference electrode which is of a substance having a melting point of the same level as or lower than the metal or alloy of which the oxygen potential is to be measured and being liquid at the measurement temperature and is open to the atmosphere, a vessel of a zirconia solid electrolyte containing 5-10% yttria or 10-20% of calcium oxide (CaO) and a lead wire which connects the reference electrode and said molten metal or alloy and its use are disclosed.

Abstract: A method for measuring concentrations of addition agents in solutions of additive mixtures, namely for monitoring additives in PbSn plating solutions, comprising the steps of: (a) preparing a basis solution which contains an electroactive species whose electroreduction reaction is sensitive to the additive of interest; (b) preparing calibration standard sample solutions comprising appropriate concentrations of all species other than the additive; (c) preparing the working solution whose additive concentration is to be determined; (d) applying a pulse voltammetry technique, at a hanging Hg drop electrode, to a sample of the basis solution located in a cell of a polarographic analyzer; (e) thereafter measuring the polarographic peak height for the indicator reaction in the basis solution; (f) adding a measured amount of the working solution to the basis solution sample in the cell; (g) thereafter measuring the peak height for the indicator reaction in the mixed solution of step (f); and (h) repeating steps (f)

Abstract: One of the fundamental limitations of voltammetric detectors in flow analysis is the problem of passivation or contamination of the working electrode. The present invention proposes a voltammetric detector based on the wall-jet principle which incorporates the concept of a replaceable working electrode. The voltammetric detector represents a significant improvement over existing detectors which are fully enclosed or sealed devices precluding easy replacement of the working electrode.The design of the present invention provides a detector where the top is fully open and where the solution volume is maintained by the outlet positioning. The other feature of the proposed detector is an optimised geometry that provides well defined wall-jet flow characteristics which is not provided in existing detectors.

Abstract: Electrode arrangement with liquid-metal electrode of controllable surface, comprising a liquid-metal reservoir, a capillary connected thereto through a controllable valve and contact means being in electric contact with the liquid-metal in the capillary. According to the invention at least one section of the capillary is formed within a metal body not reacting chemically with the liquid-metal, said metal body constituting the contact means. Preferably, the metal body is formed so that an elastic closing element of the valve fits to a surface of the metal body surrounding an opening of the capillary section formed therein.

Abstract: A mercury drop electrode for use in electrochemical experiments. The invention includes a reservoir for liquid mercury, a mercury drop capillary having upper and lower open ends and also having a chemically inert lower capillary tube portion and an electrically conductive upper capillary tube portion supported by the lower portion and in contact with the mercury in the reservoir, valve means including a valve stem having a seal at its lower end and a ferromagnetic portion at its upper end, a valve seat comprising the upper end of the upper portion of the capillary which acts in concert with the valve seal to close the valve, and actuating means operatively arranged to lift the valve seal form the seat to allow mercury to enter the capillary from the reservoir and to lower the seal to the seat to prevent mercury from entering the capillary from the reservoir.

Abstract: A reference electrode utilizes a small thin, flat membrane of a highly conductive glass placed on a small diameter insulator tube having a reference material inside in contact with an internal voltage lead. When the sensor is placed in a non-aqueous ionic electrolytic solution, the concentration difference across the glass membrane generates a low voltage signal in precise relationship to the concentration of the species to be measured with high spatial resolution.