Abstract: Systems and methods for vehicle braking signals are described herein. In some embodiments, the system and methods improve the brake lights on automobiles.

Abstract: Certain implementations of the disclosed technology may include systems and methods for multibit code communications that can provide more than one bit per input port. In an example implementation, a method is provided that can include measuring an input voltage at an input port in communication with a device. The method can include comparing the measured input voltage with a plurality of predetermined reference voltage levels, and determining, based on the comparing, a device ID. The method can further include outputting the device ID. Certain implementations may further include compensating a signal associated with the device based on the identified device ID.

Abstract: An electrical sensor is described. The electrical sensor including an electrical signal input configured to receive an electrical signal, an alarm, one or more inputs configured to set a configuration value corresponding to one or more indicators on the electrical sensor, and monitor. The monitor is coupled with the electrical signal input, the alarm, and the one or more inputs. Further, the monitor is configured to determine a characteristic of the electrical signal received on the electrical signal input. And, the monitor is configured to activate the alarm based on the configuration value set by the one or more inputs and the characteristic of the electrical signal.

Abstract: A main power supply supplies a power supply voltage to a power supply terminal of a DUT. A control pattern generator generates a control pattern including a pulse sequence. A compensation circuit intermittently injects a compensation current to the power supply terminal of the DUT via a path different from that of the main power supply. A switch is arranged between an output terminal of a voltage source and the power supply terminal of the DUT, and is turned on and off according to the control pattern.

Abstract: A structure is described that includes a first faying surface, a second faying surface for creating an electrical bond with the first faying surface, and a sensor operatively placed proximate the first faying surface and the second faying surface. The sensor includes a current port for injecting a fixed current through the electrical bond, a voltage port for sensing a voltage across the electrical bond induced by the fixed current, a processing device programmed to determine a resistance of the electrical bond based on the fixed current and sensed voltage, and a wireless interface for transmitting at least one of the sensed voltage and the determined resistance to an external device.

Abstract: Disclosed are an online alternating current detection device and method. The method includes the following steps: firstly fixedly connecting two sampling points to a segment of wire; amplifying the voltage difference of the sampling points to obtain a median value; subsequently rectifying and filtering and amplifying the median to obtain a direct current amplified value; then utilizing the amplified value, the median value, the multiplying power there between and the resistance value of the wire between the two sampling points to calculate an estimated value of an alternating current; comparing the estimated value to a reference value measured by a standard device between the two sampling points; then adjusting the multiplying power of the amplified value relative to the median until the estimated value coincides with the reference value, only then can the alternating current be measured online.

Abstract: The present invention discloses an optical module and a detection circuit thereof. The detection circuit includes: a sampling module, including a first potentiometer configured to convert a sampling current into a sampling voltage; an amplifying module, coupled to an output end of the sampling module and configured to amplify the sampling voltage; and an analog-to-digital conversion module, coupled to an output end of the amplifying module and configured to convert the amplified sampling voltage into a digital signal for detection. By arranging a potentiometer in a sampling module of a detection circuit, a resistance value of the sampling module can be adjusted, thereby adapting to responsivities of different modulators, increasing the locking speed of a modulator, preventing horizontal shifts of a locking point and a false locking point, and reducing the occupied PCB area.

Abstract: A self-powered current sensor is described. The self-powered current sensor including an electrical signal input configured to receive a current signal. Further, the self-powered current sensor includes a power circuit configured to generate a power voltage from an electrical signal. The self-powered current sensor also includes a variable resistor configured to set a value corresponding to one or more indicators on the electrical sensor and an amplifier coupled with a variable resistor and a power circuit. And, the self-powered current sensor includes an alarm coupled with an amplifier, an alarm configured to activate based on a value set by said variable resistor.

Abstract: Systems and methods for system for gripping a specimen container are disclosed. The system comprises a plurality of gripper fingers, a processor, and a system for gathering data related to a specimen container. Data related to a specimen container, such as detection of the presence of a specimen container within the gripper, measurement of specimen container dimensions and weight, detection of specimen container contents, specimen tube identification, etc. are gathered. Embodiments provide an improved automated process by simultaneously performing multiple measurements and analytical processes on the specimen container, thereby providing for faster processing of the sample that resides in the specimen container.

Abstract: A balancing resistor testing apparatus is configured for acquiring a resistance of a balancing resistor electronically connected to a supercapacitor of a series supercapacitor assembly in parallel. The balancing resistor testing apparatus includes a controller and a digital potentiometer. The controller detects a voltage across each supercapacitor of the series supercapacitor. The digital potentiometer comprising a plurality of variable resistors each of which is electronically connected to a supercapacitor in parallel, the controller controls the digital potentiometer to continuously adjust the effective resistance of each potentiometer until the controller detects that each supercapacitor has the same or very similar voltage.

Abstract: The resistance measuring device of the present invention includes switch transistors and switch conductive lines disposed between the bonding pads on a first substrate and between the bumps on a second substrate, such that the bonding pads and the bumps are conducted when the transistors are turned on, and the bonding resistance between at least one of the bonding pads and its corresponding bump can be directly measured.

Abstract: A touchscreen panel includes an upper resistive film including a first upper electrode and a second upper electrode provided at a first end and a second end, respectively, in a first direction; a lower resistive film including a first lower electrode and a second lower electrode provided at a first end and a second end, respectively, in a second direction perpendicular to the first direction; a first electric potential detecting part connected to the first upper electrode; a second electric potential detecting part connected to the second upper electrode; a third electric potential detecting part connected to the first lower electrode; and a fourth electric potential detecting part connected to the second lower electrode.

Abstract: A grid sensor significantly reduces the complexity of a production process. The cost for installing and running the grid sensor are significantly reduced and the service life, pressure and heat resistance of the grid sensor can be significantly increased over previous grid sensors. Channels, which are wider than the diameter of the wire electrodes and have a depth of less than half the thickness of the sensor board, run outwardly from the edge of the measurement cross section in the sensor board. The channels are coated by a metal layer and the wire electrodes are inserted into the periphery of the measurement cross section. The two ends of the electrode, each in one of the opposite channels, and the electrodes are fixed in the channels by means of a conductive sealing compound. In each channel, the conductive sealing compound terminates in a planar fashion with the upper side of the sensor board, and the sensor board is clamped between two clamping plates.

Abstract: A potentiostat is provided for a biosensor circuit and permits sequential and simultaneous measurements to be performed at different cells across a matrix of biosensing devices. Accordingly, a potentiostat comprises a first differential amplifier for receiving a scanning voltage at a first input terminal and a voltage at the reference electrode at a second input terminal and for generating an output voltage at an output terminal to be applied to the working electrode, wherein, when in use, a feedback loop of the potentiostat circuit is closed between the reference electrode and the working electrode.

Abstract: A method for diagnosing a position detector used in determining the position of a control means. The position detector includes a resistance track, and a first terminal in connection with its first end, and a second terminal in connection with second end of the resistance track, and a slide electrically connected to the resistance track. The slide is arranged to move in relation to the control by the effect of a position change. Additionally, the position detector includes a slide terminal in connection with the slide, an electricity supply, a voltage measurer and a signal processing unit for diagnosing measurement data. In the method, a supply voltage is arranged in the slide terminal, the output voltage of the first terminal is measured, the output voltage of the second terminal is measured, and at least a first and a second output voltage are arranged to the signal processing unit.

Abstract: The disclosure relates to a method for increasing the availability of displacement/position measuring systems on the basis of potentiometers with a slider tap in a closed control loop, the controller of which is formed by a microcontroller which is supplied with the position of the slider via an analog/digital converter. The position of a defective slider position of the potentiometer is determined within the active process task by evaluating an available control loop variable, and the reference variable of the control loop is overloaded in a defined manner such that the defective slider position is passed over during the displacement/position measurement and an intact slider position is reached.

Abstract: An electronic machine connectable to a different apparatus is disclosed. The electronic machine includes a resistance, a connector to be connected to the different apparatus, and a detecting section that detects one state from multiple states based on the resistance value of the resistance and the resistance value of a resistance included in the different apparatus connected to the connector and controls multiple parameters based on the detected one state.

Abstract: A diagnostic circuit for a potentiometer that connects a load resistor (laboratory resistor) to the slider of the potentiometer to allow a constant comparison of the contact resistance to measured values in the loaded and/or unloaded state when the slider is being adjusted, or when it is being paused at a critical point. This is accomplished by connecting a pull-up resistor to an input of the microprocessor, to which a load resistor is connected, and which is electrically connected to the slider. The slider itself is connected to an additional input of the microprocessor.

Abstract: A calibration tool for an air data sensor of a vehicle comprises a target surface which is disposable on the vehicle. The calibration tool may further comprise a light pointer which is mountable on the air data sensor and which is operative to project a beam of light toward the target surface. The air data sensor may be configured as a flow direction sensor which may include at least one of an alpha vane for measuring angle of attack or a beta vane for measuring sideslip. The flow direction sensor may be mountable in spaced relation to the vehicle via a standoff. The flow direction sensor may include a hollow pivot arm having a laser pointer mounted therewithin for projecting a beam of laser light onto the target surface.

Abstract: Disclosed is a device for sensing the opening degree of a valve, which can easily determine the upper and lower limits without using upper and lower limit switches so that, besides simplifying the mechanical structure, the device can be easily installed, maintained, and repaired. The device can avoid basic errors and improve the opening degree sensing performance without using upper and lower limit switches, cams, and a spline so that, by simplifying the mechanical structure, the device can be manufactured, installed, maintained, and repaired at a low cost, and its long-term durability is improved. The device has a main gear adapted to disengage from the meter gear when the main gear is rotated excessively so that any damage to the meter gear and potentiometer, which may occur during installation or use, is prevented.

Abstract: A method for controlling a marine vessel having a first steering nozzle, a reversing deflector and at least one of a bow thruster and a second steering nozzle is disclosed. The method comprises any of the acts of inducing a net transverse thrust to the marine vessel in response to a transverse thrust component signal, without substantially inducing any forward-reverse thrust or rotational thrust to the marine vessel, or inducing a net forward-reverse thrust to the marine vessel in response to a forward-reverse thrust component signal without substantially inducing any transverse thrust or rotational thrust to the marine vessel, or inducing a net rotational thrust to the marine vessel in response to the rotational thrust component signal without substantially inducing any forward-reverse thrust or transverse thrust to the marine vessel.

Abstract: A circuit and method for determining the wiper resistance of a potentiometer that includes the step of electrically coupling a sense resistor having a substantially constant sense resistance to the potentiometer third terminal. The potentiometer is electrically energized, and a potentiometer voltage, which is a voltage potential between the potentiometer first and second terminals, is determined. The wiper position is determined based at least in part on the determined potentiometer voltage. The sense resistor is electrically coupled to a potential that causes a wiper current to flow through the wiper and sense resistor. A magnitude of the wiper current is determined, and the wiper resistance is determined based at least in part on the potentiometer resistance, the determined potentiometer position, the determined wiper current magnitude, and the sense resistance.

Abstract: There is provided a power supply monitor circuit comprising a positive supply monitoring input, a negative supply monitoring input, and a voltage divider connected between the positive and negative supply monitoring inputs and having an intermediate node providing a potential intermediate those on the positive and negative supply monitoring inputs. A sampling circuit is connected to sample the potential at each of the positive supply input the negative supply input and the intermediate node. Also provided is a method of monitoring noise on a power supply whereby phase information from those samples is derived about the noise signals at the two said points.

Abstract: A potentiometer (PT1, PT2) has a first terminal (A1), a second terminal (A2) and an intermediate tap (ZA), a resistor being between the first terminal (A1) and the second terminal (A2) irrespective of the position of the potentiometer (PT1, PT2). In an evaluation method, a first drive voltage (GND) and at least one second drive voltage (VS), which is different than the first drive voltage, are applied to the first terminal (A1) and/or the second terminal (A2) and/or a third drive voltage (VS) is applied to the intermediate tap (ZA). The evaluation can be made from the different measurement voltages measured at the terminals.

Abstract: A portable metered flow apparatus for accurately providing calibration gas from a calibration gas source to a gas monitoring instrument in order to permit calibration/bump testing of the instrument comprising a regulator and a gas delivery device that includes a solenoid valve, an electronic timing circuit, means for providing power to the solenoid valve and the electronic timing circuit, a power switch for activating the electronic timing circuit, means for activating the release of calibration gas; and optionally one or more LED lights. A method for calibration/bump testing of a gas monitoring device utilizing the portable metered flow apparatus is also provided.

Abstract: According to some embodiments, a method of determining a resistance of probes on a contactor device is disclosed. The contactor device can include a plurality of probes disposed to contact an electronic device to be tested. The method can include electrically connecting a pair of the probes to each other, and then forcing one of a voltage onto or a current through the pair of the probes. At a location on the contactor device, the other of a voltage across or a current through the pair of the probes can be sensed. A determination relating to a resistance of the probes can be determined from the values of the forced voltage or current and sensed other of the voltage or current.

Abstract: The sensor arrangement includes: a least two sample chambers; at least two potentiometric FET-sensors, especially ISFET-sensors or ChemFET-sensors, having, in each case, a sensitive surface section, wherein each sensitive surface section lies in flow connection with its one of the sample chambers; and a reference cell having a reference medium for providing a reference potential, wherein the sample chambers are connected with the reference medium via an electrolyte bridge. The reference cell has, preferably, a potentiometric reference-FET-sensor for providing a reference potential, which is registered against the pseudo-reference-potential of a redox electrode. The potentials Udiff1, Udiff2, . . .

Abstract: A transducer in the form of a potentiometer provides an output signal indicative of a position of a component. The potentiometer comprises a body, a member moveable relative to the body and having an end portion for coupling to the component, and a resistor mounted to the body. A wiper is coupled to the member and forms a slidable electrical contact to the resistor. The potentiometer also comprises a contactor means for providing selectable contact positions to the resistor of respective first and second electrical conductors, so as to provide a selected operating section of said resistor.

Abstract: A position sensor comprises a resistive element positionable on a first surface. A pair of leads are on the resistive element, the pair of leads adapted to supply a first voltage, such as by being grounded. An intermediate lead is positioned on the resistive element between the pair of leads, the intermediate lead being adapted to provide a second voltage. A contact element is positionable on a second surface, the contact element adapted to contact at least a portion of the resistive element to detect a voltage at a contact position, the detected voltage being related to the position or movement of the second surface relative to the first surface. In another version, a position sensor comprises a resistive element comprising first and second resistive strips. A plurality of leads are positioned on each resistive strip to provide a voltage to each resistive strip.

Abstract: A system and method for pressure measurement may include the ability to readily produce a pressure measurement system. In one general aspect, pressure measurement may include a signal-converting circuit that includes a coupler, a signal biaser, and a signal span adjuster. The coupler is operable to receive a pressure-representative signal, and the signal biaser includes a thermally-insensitive voltage divider that facilitates biasing the pressure-representative signal. The signal span adjuster is coupled to the coupler and the signal biaser and includes a thermally-insensitive voltage divider that facilitates adjusting the span of the pressure-representative signal.

Abstract: A high resolution potentiometer implemented using at least two digital potentiometers connected in parallel. Each digital potentiometer is controlled to provide a corresponding resistance value, and a desired resistance value is attained by such control. The resolution is high in some range of desired resistance values and low in other ranges. A high resolution in a desired range can be attained by connecting another resistor in series with the digital potentiometers connected in parallel.

Abstract: A circuit arrangement and a method are described with which a current circuit can be monitored for correct function. A first and a second current sensor are provided in the current circuit. In a test phase, the second current sensor is switched to the current circuit. Next, a current flow is brought about through the first and the second current sensors, and the current intensity is measured via the first and second current sensors. From a comparison, an error function of the current sensor can be detected. The circuit arrangement according to the invention and the method according to the invention are particularly suitable for use in safety-oriented equipment.

Abstract: A position sensor includes a resistive element positionable on a first surface. A pair of leads are on the resistive element, the pair of leads adapted to supply a first voltage, such as by being grounded. An intermediate lead is positioned on the resistive element between the pair of leads, the intermediate lead being adapted to provide a second voltage. A contact element is positionable on a second surface, the contact element adapted to contact at least a portion of the resistive element to detect a voltage at a contact position, the detected voltage being related to the position or movement of the second surface relative to the first surface. In another version, a position sensor includes a resistive element comprising first and second resistive strips. A plurality of leads are positioned on each resistive strip to provide a voltage to each resistive strip.

Abstract: A digital potentiometer device has a potentiometer, coupled to a reference voltage, that generates a voltage that can be varied. A programmable scaling function scales the reference voltage and the potentiometer's wiper voltage depending on stored user variables. An analog-to-digital converter converts the scaled potentiometer voltage to a digital value readable by a controller circuit. The controller circuit controls the scaling function and display of the potentiometer position with the user variables.

Abstract: A digital potentiometer device has a potentiometer, coupled to a reference voltage, that generates a voltage that can be varied. A programmable scaling function scales the reference voltage and the potentiometer's wiper voltage depending on stored user variables. An analog-to-digital converter converts the scaled potentiometer voltage to a digital value readable by a controller circuit. The controller circuit controls the scaling function and display of the potentiometer position with the user variables.

Abstract: An inspection apparatus and method of electrode patterns using rolling wire probes, which includes a rolling wire rotating for performing a rolling contact sliplessly across the electrode patterns, and a control unit for controlling operations of the inspection apparatus wholly and for discriminating the electrical characteristics according to the electrical signal sensed through the rolling wire provided to the rolling wire probe. The inspection method is used flexibly with electrode patterns having various forms regardless of the change of model or design of the product, unlike the inspection method of the conventional art by the test pin block. Upon inspecting a pixel portion of the electrode pattern, a scratch is not generated by the rolling contact operation, thereby increasing yield of the finished goods.

Abstract: Embodiments of the invention describe a method and apparatus used to determine the position of a wiper on a potentiometer without the need for an external ADC. Two capacitors are each connected to an end of a potentiometer, and then are charged or discharged simultaneously by a current source or current sink attached to the wiper of the potentiometer. The time required for each of the capacitors to charge or discharge to a threshold voltage level is measured and subsequently used to determine the position of the wiper on the potentiometer.

Abstract: A resistance-type liquid level measuring apparatus which suppresses a detection voltage error due to silver sulfide within a permissible range in practical use and enables measurement indication with accuracy, and comprises a resistance-type sensor including a float 9 floating according to a liquid level, an insulating substrate 6 having a plurality of conductor electrodes 4 connected with a resistor 5, and a movable contact interlocked with a movement of the float 9 to come in contact with the conductor electrodes 4 on the insulating substrate 6, in which a material containing silver is used as a material of the conductor electrodes 4 or the movable contact, a voltage dividing resistance 11 is connected with a power source BA in series with the resistor 5, and a voltage of a connection point between the voltage dividing resistance 11 and the resistor 5 is outputted as a signal corresponding to the liquid level, and resistance values of the voltage dividing resistance 11 and the resistor 5 are set so that a v

Abstract: A system and method for measuring the alternating current series resistance of a conductor when transporting large currents on the order of several thousand amperes. The system comprises a current sensor, a current/voltage converter, a voltage divider, a voltage sensor, a null indicator, and a voltage meter. The alternating current series resistance is measured by measuring a real component of a voltage drop over a predetermined length of the conductor, deriving a measurement current from the conductor, converting the measurement current into a measurement voltage, withdrawing an adjustable portion of voltage from the measurement voltage, comparing the adjustable portion of voltage with the voltage drop, adjusting the adjustable portion of voltage to balance the voltage drop, measuring the alternating current, and determining the resistance of the conductor as a function of the value of the adjustable portion of voltage that balances the voltage drop and the measured alternating current.

Abstract: Disclosed is a method for fabricating biosensors, using hydrophilic polyurethane. Bio-active reagents, including enzymes, antibodies, antigens, cells and receptors, are mixed with hydrophilic polyurethane and the mixture is directly coated over a signal transducer to form a sensing film which serves as a signal detector. The method using hydrophilic polyurethane allows the simplification of the fabrication of biosensors without conducting complicated chemical reactions and washing steps, such as crosslinking. The bio-active reagent entrapped within the hydrophilic polyurethane film can retains its high activity for an extended period of time and the intrinsic potentiometric response of the underlying ion-selective polymeric membrane is not affected by the bio-active reagent immobilized polyurethane film coated on its sensing surface. Therefore, the biosensors are superior in specificity, selectivity, and stability.

Abstract: The invention relates to a device for measuring the position of an object that can be moved forward and backward along a fixed path, such as a closure element of an open roof construction for a vehicle. The device includes a driving unit for the object and a pulse generator, which is driven by the driving unit, for delivering pulses during the movement of the object along the path. The device further includes a slow potentiometer, which potentiometer is likewise driven by the driving unit and which is connected to the driving unit via a transmission, such that the potentiometer passes through its range of values maximally once during a complete movement of the object along its fixed path. The slow potentiometer provides a monitoring function with respect to the position signal that is based on the number of registered pulses.

Abstract: A method for calibrating a potentiometer that determines the actual resistance of the potentiometer throughout its range of motion. The potentiometer is rotated in a forward direction from its first stop position to its second stop position while resistance measurements are made based on pulses generated by an encoder coupled to the potentiometer. After the forward resistance measurements are made, a set of reverse resistance measurements are made as the potentiometer moves between the second stop position and the first stop position. A microprocessor combines the forward and reverse resistance measurements to generate an average resistance value for each angular position of the potentiometer. An individual label is then printed based on the specific resistance characteristics of the potentiometer being tested.

Abstract: A head for the linear dimension checking of pieces in machine tools or measuring machines with a support structure (1), a movable arm-set (4) including an arm (6) carrying a feeler (8) for contacting the piece (37) to be checked, a spring (17) arranged between the support structure and the movable arm-set, a first annular surface (19) fixed to the support structure, a second annular surface (18) fixed to the movable arm-set and urged by the spring into contact with the first annular surface and an electric detecting device. The detecting device includes a ring (16) made of electrically resistive material that defines the first annular surface and another ring (13) made of electrically resistive material that defines the second annular surface, a circuit (21) for applying a difference of potential across two points (22, 23) of the first ring and another circuit (30) for detecting the difference of potential across two points (24, 25) of the other ring.

Abstract: The present invention is directed to a rotary position sensor which includes a housing, connector terminals mounted in the housing, whose connecting portions are exposed inside of the housing, a base plate mounted in the housing, on which a detection circuit is formed, and a rotor rotated relative to the base plate. Terminal portions of the detection circuit are exposed on a surface of the base plate. The terminal portions of the detection circuit are placed to face the connecting portions of the connector terminals. And, a conductive resilient member is disposed between the terminal portions of the detection circuit and the connecting portions of the connector terminals, so that the conductive resilient member allows electrical connection only between the terminal portions of the detection circuit and the connecting portions of the connector terminals.

Abstract: A main sensor 101a and a subsensor 101b are two sensors adapted to operate in the same direction. A voltage of the same polarity is applied to both the sensors 101a and 101b from a common power supply of a voltage application 100. Then, an offset 103 causes an output value of the subsensor 101b to deviate from an output value of the main sensor 101a by a predetermined value. When the difference between outputs of both the sensors is outside a predetermined range, an abnormality decision 102 decides that an anomaly occurs in the sensor.

Abstract: The invention relates to a device for measuring the position of an object that can be moved forward and backward along a fixed path, such as a closure element of an open roof construction for a vehicle. The device includes a driving unit for said object and a pulse generator, which is driven by said driving unit, for delivering pulses during the movement of the object along said path. The device further includes a slow potentiometer, which potentiometer is likewise driven by the driving unit and which is connected to the driving unit via a transmission, such that the potentiometer passes through its range of values maximally once during a complete movement of the object along its fixed path. The slow potentiometer provides a monitoring function with respect to the position signal that is based on the number of registered pulses.

Abstract: A device for automatically measuring a concentration of a developing agent in a developing bath includes a voltage generator capable of generating at least one voltage ramp provided to feed a three-electrode cell; a potentiostat provided to maintain a constant potential difference between two electrodes; a peak detector provided to identify the maximum current flowing in the three-electrode cell that corresponds to the developing agent concentration; and a display unit provided to show the maximum current.

Abstract: A droplet forming flow cytometer system allows high speed processing without the need for high oscillator drive powers through the inclusion of an oscillator or piezoelectric crystal such as within the nozzle volume or otherwise unidirectionally coupled to the sheath fluid. The nozzle container continuously converges so as to amplify unidirectional oscillations which are transmitted as pressure waves through the nozzle volume to the nozzle exit so as to form droplets from the fluid jet. The oscillator is directionally isolated so as to avoid moving the entire nozzle container so as to create only pressure waves within the sheath fluid. A variation in substance concentration is achieved through a movable substance introduction port which is positioned within a convergence zone to vary the relative concentration of substance to sheath fluid while still maintaining optimal laminar flow conditions. This variation may be automatically controlled through a sensor and controller configuration.

Abstract: The present invention is a method of detecting reaction in blood caused by the presence of a foreign substance in the blood, comprising the steps of: establishing a potential across a predetermined spatial volume; passing a first portion of the blood through the predetermined spatial volume; substantially continuously measuring the potential across the predetermined spatial volume over a first predetermined period of time; comparing the measured potential with a baseline; and calculating the total volume of solids in the first portion of the blood as a function of a total absolute deviation of the measured potential from the baseline. The same procedure is then followed with a second portion of the blood, after it has been exposed to the substance whose reaction is being determined. The two calculations are then compared, with a positive reaction being indicated when the two measured solid volumes are measurably different.

Abstract: Apparatus for sensing and characterizing particles (e.g., blood cells or ceramic powders) suspended in a liquid medium comprises a conduit through which the particle suspension is caused to pass simultaneously with an electrical current. According to the invention, the interior wall of the conduit effectively varies in resistivity along the length of the conduit to define a delimited central region of high electrical resistivity which is smoothly contiguous on its opposing boundaries to uninsulated distal elements of lesser electrical resistivity. The delimited central region of the conduit functions as a Coulter volumeter conduit. The uninsulated distal elements of the conduit are made to have a dimension along the conduit wall which is at least equal to the axial extent of the effective ambit electric fields of a traditional Coulter volumeter conduit having a cross-sectional geometry identical to that of the delimited central region of high resistivity in the improved volumeter conduit.