Abstract: Apparatus and method for non-invasively determining the level of a constituent of a patient's blood drawn though an elastomeric tubing to a dialysis machine deforms the tubing in the slot of a measuring head having two points of different transverse length with a transmit/receive sensor at each point that transmits a signal through the tubing and the blood and is reflected back to it from the tubing internal wall. The round trip transit time of the signal at each sensor is measured and the blood sound velocity is calculated from the two round trip transit times and the differential of the transverse lengths at the two points. Blood hematocrit level, which is related to blood volume, is calculated from the calculated sound velocity and an empirical relationship.

Abstract: Apparatus for non-invasive measuring of the sound velocity of a fluid flowing in a tubing having a small internal diameter for the fluid passage as compared to the tubing wall thickness and having points of two different and known transverse length with a sensor mounted at each point and a delay line adjacent to the tubing at each point. Each sensor is connected to a circuit that provides ultrasonic energy signals that are transmitted through the tubing walls, the flowing fluid and the delay line to be reflected back to the sensor from which the round trip transit time of the signals is measured and the sound velocity calculated from the two measured round trip transit times and the differential between the known transverse lengths.

Abstract: Apparatus for determining the sound velocity of a liquid in a specimen having two walls between which the liquid is contained with one of the walls being deformable has a sensor including a transducer for transmitting ultrasonic energy signals between the specimen walls and apparatus for deforming the specimen wall by a known distance from a first to a second position relatively spaced from the transducer and an electronic circuit including a microprocessor for measuring first and second transit times of the signals through the liquid between the specimen walls for each of the specimen deformable wall first and second positions, and for calculating the sound velocity of the liquid based upon the known distance and the two measured transit times. Where blood is the liquid values of parameters such as glucose and hematocrit are obtained based on algorithms pre-programmed in the microprocessor.

Abstract: Apparatus and method for non-invasive measuring of the sound velocity of a fluid, such as a liquid, flowing in a tubing having points of two different and known transverse length has one sensor mounted at each point connected to a circuit that provides signals to each sensor that are returned to it after passing through the tubing wall and flowing fluid and reflection from the tubing internal wall opposing each sensor and from which the round trip transit time of the signals is measured and the sound velocity calculated from the two measured round trip transit times and the differential between the known transverse lengths. Flexible tubing is placed in the slot of a measuring head which deforms it to provide the two points at one location or the slot has two sections of different transverse length along its length with a point at each section.

Abstract: A dialysis system that includes a dialysis machine, a tube connected to the dialysis machine, and a sensor system. The sensor system includes a head having a slot configured to receive the tube and a plurality of sensors secured to the head adjacent the slot. At least one of the plurality of sensors includes a light emitting element configured to transmit light through the tube when the tube is disposed in the slot and a light receiving element configured to receive the light emitted by the light emitting element after the light passes trough the tube.

Abstract: Apparatus for non-invasive measuring of the sound velocity of a fluid flowing in a tubing having a small internal diameter for the fluid passage as compared to the tubing wall thickness and having points of two different and known transverse length with a sensor mounted at each point and a delay line adjacent to the tubing at each point. Each sensor is connected to a circuit that provides ultrasonic energy signals that are transmitted through the tubing walls, the flowing fluid and the delay line to be reflected back to the sensor from which the round trip transit time of the signals is measured and the sound velocity calculated from the two measured round trip transit times and the differential between the known transverse lengths.

Abstract: Apparatus for determining the sound velocity of a liquid in a specimen having two walls between which the liquid is contained with one of the walls being deformable has a sensor including a transducer for transmitting ultrasonic energy signals between the specimen walls and apparatus for deforming the specimen wall by a known distance from a first to a second position relatively spaced from the transducer and an electronic circuit including a microprocessor for measuring first and second transit times of the signals through the liquid between the specimen walls for each of the specimen deformable wall first and second positions, and for calculating the sound velocity of the liquid based upon the known distance and the two measured transit times. Where blood is the liquid values of parameters such as glucose and hematocrit are obtained based on algorithms pre-programmed in the microprocessor.

Abstract: Apparatus and method for non-invasively determining the level of a constituent of a patient's blood drawn though an elastomeric tubing to a dialysis machine deforms the tubing in the slot of a measuring head having two points of different transverse length with a transmit/receive sensor at each point that transmits a signal through the tubing and the blood and is reflected back to it from the tubing internal wall. The round trip transit time of the signal at each sensor is measured and the blood sound velocity is calculated from the two round trip transit times and the differential of the transverse lengths at the two points. Blood hematocrit level, which is related to blood volume, is calculated from the calculated sound velocity and an empirical relationship.

Abstract: Apparatus and method for non-invasive measuring of the sound velocity of a fluid, such as a liquid, flowing in a tubing having points of two different and known transverse length has one sensor mounted at each point connected to a circuit that provides signals to each sensor that are returned to it after passing through the tubing wall and flowing fluid and reflection from the tubing internal wall opposing each sensor and from which the round trip transit time of the signals is measured and the sound velocity calculated from the two measured round trip transit times and the differential between the known transverse lengths. Flexible tubing is placed in the slot of a measuring head which deforms it to provide the two points at one location or the slot has two sections of different transverse length along its length with a point at each section.

Abstract: A measuring head has a base and extending spaced apart vertical sidewalls that form a slot into which a tube through which a fluid flows is placed and at least one sensor element mounted in at least one of the sidewalls to detect a characteristic of the flowing fluid. At least one through passage is formed in each of the sidewalls that are aligned opposing each other to form a pair of passages through which a strap is passed above the tube in the head slot and a fastener holds the strap bound to the sidewalls to retain the tube in the slot. One embodiment has a pair of the sidewall slots on each side of a sensor element mounted in a sidewall. A passage also can be provided in the head base through which a strap can pass and then be passed through a pair of the sidewall passages.

Abstract: An ultrasonic sensor for measuring the level of liquid in a vessel has an elongated tubular probe, a tube within the probe, and a transducer that converts electrical energy to ultrasonic energy mounted at or near one end of the tube so as to transmit ultrasonic energy horizontally across the probe. An element having a surface that reflects ultrasonic energy is at an angle, preferably of about 45°, to the probe longitudinal axis opposite to an ultrasonic energy emitting part of the transducer to reflect ultrasonic energy received from the transducer upwardly in the probe to an air-liquid interface from which it is downwardly reflected to the angled reflector element that directs the energy reflected from the interface back to the transducer for conversion to an electrical signal that is used by an electronic module to measure the liquid level in the probe which is the liquid level in the vessel.

Abstract: A method and apparatus for measuring the sound velocity of a flowing fluid includes a cartridge having a hollow interior through which the fluid flows formed by first and second chambers of different diameters that define first and second walls extending toward the cartridge longitudinal axis from which energy transmitted by a single sensor mounted in the cartridge is reflected back to the sensor. An electronic circuit includes a microprocessor that is programmed with the distance between the first and second walls and that measures the round-trip transit time of the signal energy transmitted to and reflected from each of the first and second walls and calculates the sound velocity of flowing fluid using the two measured round trip transit times and the programmed value of the fixed distance between the walls.

Abstract: A system and method for measuring the flow rate of a liquid in a tube non-invasively has a heating element that generates energy that is applied to the liquid to produce a heat marker that is detected by a temperature sensor located at a known distance from the heating element and the flow rate is calculated from measuring the travel time of the heat marker from the heating element to the sensor. A second temperature sensor measures the ambient temperature of the liquid before the heat marker is produced and detection of the heat marker is made on the basis of the difference between the ambient temperatures and the temperature of the heat marker.

Abstract: A dialysis system that includes a dialysis machine, a tube connected to the dialysis machine, and a sensor system. The sensor system includes a head having a slot configured to receive the tube and a plurality of sensors secured to the head adjacent the slot. At least one of the plurality of sensors includes a light emitting element configured to transmit light through the tube when the tube is disposed in the slot and a light receiving element configured to receive the light emitted by the light emitting element after the light passes trough the tube.

Abstract: An ultrasonic sensor for measuring the level of liquid in a vessel has an elongated tubular probe, a tube within the probe, and a transducer that converts electrical energy to ultrasonic energy mounted at or near one end of the tube so as to transmit ultrasonic energy horizontally across the probe. An element having a surface that reflects ultrasonic energy is at an angle, preferably of about 45°, to the probe longitudinal axis opposite to an ultrasonic energy emitting part of the transducer to reflect ultrasonic energy received from the transducer upwardly in the probe to an air-liquid interface from which it is downwardly reflected to the angled reflector element that directs the energy reflected from the interface back to the transducer for conversion to an electrical signal that is used by an electronic module to measure the liquid level in the probe which is the liquid level in the vessel.

Abstract: Apparatus for measuring the level of liquid in a container has a substrate on which a plurality of piezoelectric elements are mounted that are to transmit ultrasonic energy upwardly through the bottom of a container placed on and supported by the substrate into the container and to receive ultrasonic energy reflected back from the liquid/air interface within the container from which the round trip time can be measured and the liquid level calculated. The plurality of piezoelectric elements are of predetermined shapes and mounted spaced apart on the substrate in an array to accommodate containers with different shape bottoms.

Abstract: A non-invasive dry coupled disposable/reusable ultrasonic sensor has a housing and a piezoelectric element at one end of the housing to which connected signal leads are connected that extend out from the housing. A piece of double-sided adhesive tape has one adhesive side secured directly to the face at the one end of the housing with the other adhesive side to be secured directly to the outer surface of a pipe or vessel. The tape can cover the entire face of the one end of the housing or only that part that the piezoelectric element faces.

Abstract: An integrated multi-function sensor system has a head having a slot to accept a tube of a deformable material and a plurality of sensor elements mounted in the walls of the head slot to confront a tube in the slot, each sensor element being for affecting sensing of a condition relating to a liquid in the tube. An integrated electronic circuit including a microprocessor operates to determine the various conditions of a liquid flowing in the tube sensed by the sensor elements, which conditions include detection of air bubbles and/or particles by ultrasonic sensing elements, detection of an occlusion in the liquid flow by sensing the deformation of the tube wall by a force sensing element, determining the temperature of the liquid by an infrared temperature sensing element, and determining the color of the liquid by optical elements.

Abstract: A system using ultrasonic energy for detecting and quantifying air bubbles and/or particles in a liquid flowing in a tube by a non-invasive and non-destructive technique has an ultrasonic sensor having piezoelectric transmitter and receiver elements placed opposing on the outside of the tube wall and energy in the ultrasonic frequency range is transmitted from the transmitter element to the receiver element. The received ultrasonic energy is amplified and detected and preferably split into a steady state (DC) component and a varying or transient (AC) component respectively indicative of the absence and the presence of an air bubble or a particle in the liquid. The two components of the signal are applied to an A/D converter whose output is supplied to a microprocessor which uses the digital data that corresponds to the presence of the varying transient component to indicate the presence of an air bubble and/or a particle and to measure its characteristics.

Abstract: A system for determining pressure change in a liquid flowing in a tube of an elastic material has a sensor head having a slot and a pair of piezoelectric elements mounted in opposing walls of said slot between which the tube is placed in contact with the opposing elements. An electronic circuit generates periodic bursts of electro-mechanical energy from one of the elements that is transmitted through the tube to be received by the other element to be converted to an electrical signal from which is measured the travel time value of the energy through the tube and liquid therein and the amplitude value of the received signal which values are compared to at least one of base line travel time and amplitude values to determine a change of pressure of the liquid flowing in the tube.