Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
  • G01N27/403—Cells and electrode assemblies
  • G01N27/414—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
  • G01N27/4148—Integrated circuits therefor, e.g. fabricated by CMOS processing
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
  • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
  • H01L2224/42—Wire connectors; Manufacturing methods related thereto
  • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
  • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
  • H01L2224/4805—Shape
  • H01L2224/4809—Loop shape
  • H01L2224/48091—Arched
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
  • H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
  • H01L2224/732—Location after the connecting process
  • H01L2224/73251—Location after the connecting process on different surfaces
  • H01L2224/73265—Layer and wire connectors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/30—Technical effects
  • H01L2924/301—Electrical effects
  • H01L2924/3011—Impedance
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/30—Technical effects
  • H01L2924/301—Electrical effects
  • H01L2924/3025—Electromagnetic shielding

Definitions

• the invention relates to a chemosensitive transducer for the selective determination of a chemical property of a fluid, with at least one field effect transistor, the gate of which is connected to an associated measuring electrode, which is covered with a membrane that is sensitive to the chemical property, and with an encapsulation that covers the entire transducer with the exception of the membrane isolated from the fluid.
• RNA for antibody / antigen or for hydridlesse DNA / RNA for antibody / antigen or for hydridlesse DNA /.
• chemosensitive groups RNA for antibody / antigen or for hydridlesse DNA /.
• transducers are in medicine, about se to Blutanaly ⁇ , monbetician in clinical chemistry, for the therapy control Hor ⁇ , In ' Stammions- and tumor diagnosis, and also in the fermentation control, food analysis, and environmental analysis as well as for process control a ⁇ settable.
• a chemosensitive transducer with the features specified in the preamble of claim 1 is known from EP-B-0 065 350.
• a field-effect transistor is formed in a semiconductor substrate, the gate of which is connected via a laterally adjoining conductor to a measuring electrode arranged on the same side of the substrate.
• the measuring electrode is equipped with a chemical the sensitive property of the sensitive membrane or layer, which is applied by electroplating, sputtering or vapor deposition.
• the field effect transistor is encapsulated against the fluid to be examined by a protective layer which consists of an epoxy resin or silicone rubber.
• the transducer constructed in this way With its sensitive membrane, is immersed in the fluid to be examined, a potential arises due to ion exchange reactions between the electroactive substance of the membrane and the fluid at the gate electrode of the field-effect transistor, which influences its channel conductivity.
• a potential arises due to ion exchange reactions between the electroactive substance of the membrane and the fluid at the gate electrode of the field-effect transistor, which influences its channel conductivity.
• potentiometric metric or a perometrische measurement a corresponding "Talking output signal can be extracted, which is proportional to the concentration of the parameter being measured.
• the voltage caused by the ion exchange reaction mentioned is in the mV range, but the ohmic loading capacity of the membrane is in the pA to fA range.
• Another difficulty with the known transducers is that they can only be used for the detection of chemical properties for which membranes are sensitive, which can be applied to the measuring electrode by the above-mentioned methods. Description of the invention
• the invention is based on the object of specifying a chemosensitive transducer which has a higher sensitivity compared to known chemosensitive transducers and which is at the same time insensitive to electrical influences and to temperature fluctuations, it also being able to be configured sensitively for such properties should be that can only be detected with less stable membrane substances.
• a carrier plate is provided, on one side of which the measuring electrode and on the other side of which an amplifier circuit containing the field effect transistor are arranged; furthermore, the measuring electrode is electrically connected to the gate of the field effect transistor via a conductor passing through the carrier plate.
• the arrangement of the measuring electrode and amplifier circuit on opposite sides of a carrier plate with through-contacting through the carrier plate results in the shortest distances between the respective measuring electrode and the associated amplifier shell with small overall dimensions of the transducer and free design options with regard to the size and number of measuring electrode surfaces ⁇ device with a correspondingly high signal / noise ratio.
• the converter according to the invention is thus more sensitive than conventional converters.
• the construction according to the invention allows a largely free choice of the design of the measuring electrode (s) and thus an adaptation to a wide variety of measuring problems.
• all membrane types can be used as membranes be used in conventional ion-selective electrodes.
• the amplifier circuit can also be designed using a wide variety of techniques, for example, the converter can be constructed inexpensively using hybrid technology or thin-film technology even in small quantities.
• the carrier plate consists of an insulating material, which is in particular SiO-, a ceramic material such as I-C. Glass, an epoxy resin or a plastic material can be (claim 3).
• the carrier plate not only ensures the necessary stability with a small thickness, but also reliably shields the amplifier circuit (s) against environmental influences.
• a ceramic material such as Al-O., - ceramic is suitable, for example, for applying the material of the measuring electrode, conductor layer and other conductor tracks in thick-film technology.
• the measuring electrode, the conductor passing through the carrier plate and optionally the conductor layer consist of a material which is chemically inert to the fluid, so that there is no reaction with the fluid to be examined and in particular for the application of the membranes practically any auxiliary substances (solvents, reducing and oxidizing agents, radicals for coupling and polymerizations) allowed.
• auxiliary substances solvents, reducing and oxidizing agents, radicals for coupling and polymerizations
• Such materials are for example gold, platinum, silver, palladium or alloys thereof or a conductive polymer such as e.g. Polypyrrole.
• the area of the measuring electrode can be limited by a mask plate applied to the carrier plate.
• the measure of claim 9, according to which the mask plate covers the bore, is useful for further protection of the amplifier circuit provided in the encapsulation.
• the insulator layer covering the bore and provided between the mask plate and the carrier plate also serves to further seal the through-contact.
• This insulator layer can preferably consist of Si0 2 , polyimide, epoxy resin, aluminum oxide or a silicone resin.
• a ceramic in particular also forms a good electrical insulator and is chemically inert, ie it does not react with the fluid to be examined and is physiologically indifferent.
• the overpressure filling of the converter housing with an inert gas represents an additional measure for protecting the amplifier circuit against penetrating water vapor and prevents oxidation of the electronic components, for example in the case of autoclaving processes, as can be carried out with temperature-stable sensors.
• the sensor channels each consist of a pair of sensors whose potentials are determined with respect to a reference solution contact and subtracted from one another.
• One electrode surface is coated with the desired membrane, the other with the same, but "carrier-free" mixture.
• Carrier-free means that the membrane or layer does not have the sensitive component.
• the difference formation eliminates potential instabilities of the reference solution contact and unspecific matrix effects of the membranes, such as those caused by the diffusion of lipophilic blood lipids.
• I is a schematic representation of a chemosensitive transducer in use
• Fig. 2 shows a partial longitudinal section through the
• FIG. 3 shows a plan view of the surface of the carrier plate shown in FIG. 2 carrying the amplifier circuit
• Fig. 6 characteristics of a converter according to the invention.
• a chemositive transducer 10 is immersed in the fluid 11 to be examined and is connected via external supply lines to a voltage supply 12 and a display device 13, which is, for example, a line recorder can act connected.
• the transducer 10 is provided with two differential sensor pairs 14 and a reference solution contact 15 on its surface facing the viewer in FIG. 1.
• Each differential sensor pair 14 contains an active sensor 16 and a passive sensor 17.
• the active and passive sensors of each differential sensor pair 14 are arranged symmetrically with respect to the reference solution contact 15. 2 shows one of the active sensors 16 with associated electronics in detail.
• the sensor 16 comprises a coating applied to the top of a group consisting of A1 2 0, ceramic carrier plate 18 measuring electrode 19, the gegen ⁇ on the underside of the carrier plate layer 18 is a printed conductor is applied 20th
• An amplifier circuit 22 is arranged on the conductor layer 20 with the interposition of an SiO 2 insulating layer 21, which can be a commercially available integrated circuit and is briefly explained below for the examples with reference to FIGS. 4 and 5 .
• the gate of an input field effect transistor of the amplifier circuit 22 is connected to the measuring electrode 19 via a wire 23 and a through-contacting connecting conductor 24.
• the conductor 24 runs through a microbore which passes through the carrier plate 18 and is produced, for example, by means of a laser beam and has a diameter in the range of less than 0.1 mm.
• the support plate 18 is coated in the relevant surface areas with gold printing paste, with which the microbore is simultaneously filled. When the printing paste burns, a conductive gold layer forms on the wall of the bore.
• Fig. 3 shows the spatial design of the conductor layer 20, the SiO 2 insulating layer 21 applied thereon and the integrated amplifier circuit 22 mounted thereon.
• the connecting conductor 24 penetrating the microbore ends in a connecting lobe 25 on which the bonding wire 23 is attached.
• a mask plate 27 made of A1 2 0 ceramic is applied, which has a sensor opening 28 in the area of the measuring electrode 19.
• the microbore penetrated by the conductor 24 is located outside of this sensor opening 28 and is therefore covered by the mask plate 27 and additionally sealed by the SiO 2 layer 26.
• the measuring electrode 19 is coated with a membrane 29 which contains a substance sensitive to the chemical property to be detected.
• the sensor opening 28 formed in the mask plate 27 in conjunction with the measuring electrode 19 provided on the carrier plate 18 forms a trough-like depression with a defined base area.
• the membrane 29 can therefore be applied very easily in liquid form, a metered amount of liquid resulting in a membrane of a predetermined thickness.
• this application method is also suitable for sensitive materials which cannot be applied by conventional methods such as sputtering or vapor deposition.
• the use of the ceramic mask plates 27 also makes it possible to remove a used membrane and to replace it with a new one, so that the converter as a whole can be used repeatedly.
• a passive sensor 17 does not fundamentally differ from the structure described in FIG. 2 for an active sensor 16. He also has a membrane that up on the sensitive component, which makes up about 1% of the membrane mass in the membrane 29 of the active sensor 16, has the same composition.
• the reference solution contact 15 shown in FIG. 1 differs from the structure shown in FIG. 2 in that the measuring electrode is exposed without a membrane and no separate wiring is provided.
• the reference solution contact 15, which conveys the reference potential for the entire converter, is connected to the respective amplifier circuit 22 in the manner described below.
• the measuring electrode 19 and the conductor layer 20 with the ceramic carrier plate 18 located therebetween form a capacitor which is low
• Input capacitance of the converter and a shielding of the high-voltage antenna which results in a range of 10 15 ⁇ against stray electrical fields.
• FIG. 2 also shows a cover 30 which encapsulates the amplifier circuit 22 attached to the underside of the carrier plate 18 in connection with the carrier plate 18.
• the cover 30 also consists of A1 2 0. Ceramics.
• the space inside the encapsulation is filled with an inert gas under excess pressure in order to counteract the penetration of water vapor from the outside and to prevent oxidation of the electronic components under the influence of temperature.
• the cover 30 can extend over the entire rear side of the converter 10 shown in FIG. 1 and surrounds the electronics of all sensors 16, 17.
• the converter can be equipped with two (or even more) pairs of differential sensors 14 makes it possible, with an appropriate choice of the selective substances active sensors 16 determine two or more chemical properties of the fluid 11 simultaneously.
• the active sensor 16 is connected to the input field effect transistor of a first operational amplifier stage 31 and the passive sensor 17 is connected to the input field effect transistor of a second operational amplifier 32.
• Very high-impedance primary stages R in - 10 15 '
• the low-impedance output signals of the amplifiers 31 and 32 are connected to the two inputs of a differential amplifier 33, the output signal of which forms the measurement signal.
• the reference solution contact 15 is coupled via a resistor 34 to the input of the differential amplifier 33 to which the signal of the passive sensor 17 is applied, while a trim input 35 is coupled to the output of the active sensor 16 via a further operational amplifier 36 and a further resistor 37 Input of the differential amplifier 33 is coupled.
• the reference solution contact 15 is also connected to the analog Erdkle me 38 of the converter.
• the conductor layer 20 is connected to the output of one of the operational amplifiers 31, 32, so that the impedance-converted input signal is applied to the shielding surface.
• the circuit shown in FIG. 4 with its essential components forms an example of the amplifier circuit, designated 22 in FIG. 2, designed in an integrated form.
• the transducer described allows miniaturization of the measuring system and the membrane surfaces with largely variable size and shape.
• the converter requires only low manufacturing and development costs and can be designed for a wide variety of applications.
• the sensors have short response times. By equipping with several sensors, several parameters can be measured simultaneously. When using several membranes with different selectivities, extensive electronic elimination of the cross selectivities of individual ones is necessary
• Differential sensor pairs possible through a downstream electronics.
• the signal detection is integrated in the converter, so that the output signal can be used for display without further processing.
• FIG. 6 shows the characteristic curves of a sensor according to the invention for different ions.
• the electrode surfaces are sensitized with PVC liquid membranes without restricting the general inventive concept.
• Membrane mixtures known from the literature can be used for this. According to the difference concept, both a carrier-containing and a carrier-free membrane are used for each type of ion.
• the procedure for applying the membranes to the electrode surfaces is as follows: After drying the sensor over CaCl 2 , 7 ⁇ l of a 21% solution of the PVC membranes in THF are pipetted into the corresponding electrode wells. After the THF has evaporated, this process is repeated. The membranes are then conditioned in an electrolyte mixture.
• the geometry of the sensor zone is precisely defined by the electrode mask, so that membranes of the same thickness can be reproducibly produced by simple liquid metering. Since the membranes are fixed to the surface of the electrode by adhesion, they can be removed again and the sensor module can be re-coated after cleaning.
• the following table describes the composition of the sensitive membranes for the ions exemplified in FIG. 6.
• the membrane compositions correspond to the mixtures described for classic ion-selective electrodes.
• the difference membranes differ from the sensitive membranes in that there is no carrier.
• TEHP tris (2-ethylhexyl) phosphate
• oNPOE ortho-nitrophenyl octyl ether
• the response curves of the sensor according to the invention described above for calcium ions are shown in partial image (I), in partial image (II) for ammonium ions and in partial image (III) for protons.
• the response curves of drawing files I and II apply to aqueous solutions of the chloride salts, the response behavior of the proton sensor is given for 500 mM (filled measuring points) and for 50 mM (unfilled measuring points) sodium phosphate buffer solution.
• the response times and the determined gradients in the linear range of the sensors are summarized in the partial image (IV).
• the sensor according to the invention can be used for a wide variety of measurements in the field of medical technology, chemical analysis technology, environmental protection, etc.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Electrochemistry (AREA)
• Molecular Biology (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Computer Hardware Design (AREA)
• Physics & Mathematics (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
• Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)

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Citations (8)

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• 1988
  • 1988-08-11 DE DE3827314A patent/DE3827314C1/de not_active Expired
• 1989
  • 1989-08-09 WO PCT/DE1989/000525 patent/WO1990001694A1/de not_active Ceased
  • 1989-08-09 DE DE8989908966T patent/DE58903464D1/de not_active Expired - Lifetime
  • 1989-08-09 JP JP1508448A patent/JPH07109413B2/ja not_active Expired - Lifetime
  • 1989-08-09 EP EP89908966A patent/EP0382831B1/de not_active Expired - Lifetime
  • 1989-08-09 US US07/466,303 patent/US5039390A/en not_active Expired - Fee Related

Patent Citations (8)

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