Abstract: A gas bubble detector having a modulated IR source focused through a bandpass filter onto a venturi, formed in a sample tube, to illuminate the venturi with modulated filtered IR to detect the presence of gas bubbles as small as 0.01 cm or about 0.004" in diameter in liquid flowing through the venturi. Means are provided to determine the size of any detected bubble and to provide an alarm in the absence of liquid in the sample tube.

Abstract: A conductance measurement circuit to measure conductance of a solution under test with an output voltage proportional to conductance over a 5-decade range, i.e., 0.01 uS to 1000 uS or from 0.1 uS to 10,000 uS. An increase in conductance indicates growth, or multiplication, of the bacteria in the test solution. Two circuits are used each for an alternate half-cycle time periods of an alternate squarewave in order to cause alternate and opposite currents to be applied to the test solution. The output of one of the two circuits may be scaled for a different range optimum switching frequency dependent upon the solution conductance and to enable uninterrupted measurement over the complete 5-decade range. This circuitry provides two overlapping ranges of conductance which can be read simultaneously without discontinuity thereby eliminating range switching within the basic circuitry.

Abstract: A precision bridge measurement circuit connected to a current source providing a linear output voltage versus resistance change of a variable resistance (resistance temperature transducer) including a voltage follower in one branch of the bridge so that the zero setting of the transducer resistance does not depend upon the current source or upon an excitation voltage. The zero setting depends only on the precision and stability of the three resistances. By connecting the output of an instrumentation amplifier to a feedback resistor and then to the output of the voltage follower, minor nonlinearities in the resistance-vs-temperature output of a resistance-temperature transducer, such as a platinum temperature sensor, may be corrected. Sensors which have nonlinearity opposite in polarity to platinum, such as nickel-iron sensors, may be linearized by inserting an inverting amplifier into the feedback loop.

Abstract: An improved electro-optical ion detector comprising a channel electron multiplier assembly located at the angled focal plane of the magnetic sector of a scanning mass spectrometer with a twisted fiberoptic window with a means for precisely optically coupling the assembly to the twisted fiberoptic window. Means are provided for precisely spacing the entrance end of said twisted fiberoptic window in the form of a foil of a selected thickness. Also disclosed is a method for making an improved electro-optical ion detector.

Abstract: A scanning mass spectrometer (10) in combination with an electro-optical detector (100) which enable greatly increased speed of mass determinations by detecting a limited range of masses simultaneously, thus reducing the number of discrete magnetic field adjustments required over a large range of masses. The electro-optical detector (100) includes a channel electron multiplier assembly (94) with the surface of an image plate (80) located along the ion focal plane (44) and at an angle to the exit plate (106) of the magnetic sector (26) and a fiberoptic window (134) of a special shape optically coupled between the angled image plate (80) and a photodiode detector array (140).

Abstract: A gas analyzer (10) for detecting low concentrations of a specific gas which has a sample chamber comprising passages (14, 30, and 32) through which radiant energy is directed and which is pressure modulated by a loud speaker (36) both of which provide a radiant energy signal which is detected by a beam splitter (82) having a measurement channel (86) directed to a measurement detector (92) and a reference channel (84) with a reference cell (94), containing gas of the type being analyzed, directed to a reference detector (90). Both detectors (92, 90) produce a signal, and these signals and a cross channel normalization constant are processed by an algorithm. The loudspeaker (36) is isolated from the sample chamber by a flexible diaphragm (42) to eliminate phase changes in the pressure modulated output of the loud speaker (36).

Abstract: A respiratory CO.sub.2 detector (10) comprising an infrared lamp source (44) and an infrared detector (50) responsive thereto forming an optical path for detecting the change in CO.sub.2 concentration, or an obstruction in a cuvette (42). The output of the infrared detector (50) provides a high and low voltage signal to be applied to a feedback control loop (12) and to an output circuit (14).The feedback control loop (12) includes a peak detector (22), a contamination detector (24), a pulse-width modulator (26) and a low pass filter (28), the latter providing a DC bias on the infrared lamp (44). The peak detector (22) is connected to the pulse-width modulator (26) to maintain the lamp voltage constant and is connected to comparators (56,62) to compare both outputs of the peak and contamination detectors (22,24). The contamination detector (24) will respond to blockage in the cuvette (42).

Abstract: Disclosed is a method of making electrical connections to thin film coatings and the electrical connector formed thereby especially useful in a fluid flowmeter. The film with its conductive coating is pressed against a rigid, relatively long, connector bar by conductively coated pads of elastomeric material at a selected controlled pressure with the electrical connections to the film coating being made through the bar and pads. Utilizing this method, localized high stress area which cause damage to the thin film are avoided, and low current densities are accomplished by the controlled contact pressure over a large area of the film coating.

Abstract: In a flowmeter system having a transducer assembly defining a path for confining the flow of fluid medium there through and with first and second acoustic transducer elements disposed along said flow path for generating and receiving acoustic compression waves in the fluid medium, a phase-locked loop transmitter/receiver system including a voltage-controlled oscillator for adjusting the frequency of the acoustic compression waves to maintain the compression wavelength constant, together with circuitry for measuring the phase difference of the received acoustic compression waves relative to the applied electrical signal and circuitry for producing a signal representative of both the velocity of sound in the fluid medium and the direction and magnitude of the flow, the improvement in the circuitry which enables operation over a wider range of fluid density by causing the operating phase of the system phase-locked loop to vary in a continuous manner according to a previously determined relationship of phase-vers

Abstract: A transducer assembly comprising an inner, primary, transducer having a pair of transducers fixed to a liner or cavity for providing the fluid compression sending and receiving signals for measuring the velocity and change of composition of fluid in the cavity which is being inspired and expired by a patient in a setting, such as in an intensive care unit of a hospital. The inner transducer is disposed in a heated housing to maintain the temperature of the inner transducer at a temperature above the saturation point of the fluid being measured and is further provided with (1) an acoustical absorber to prevent sound energy from the connection tubes, which connect the transducer assembly to endotracheal tubing, from adversely affecting fluid measurements and, (2) water absorbing material to prevent water, which might condense in the connecting tubing, from entering the inner transducer and affecting the fluid measurements.

Abstract: Electrical connections to thin film coatings, especially useful in a fluid flowmeter, have a conductive coating pressed against a rigid, relatively long, connector bar by conductively coated pads of elastomeric material at a selected controlled pressure, with the electrical connections to the film coating being made through the bar and pads. Utilizing this method, localized high stress areas which cause damage to the thin film are avoided, and low current densities are accomplished by the controlled contact pressure over a large area of the film coating.

Abstract: A system for telemetering data from a patient to a monitor permitting direct connection of patient's sensors and transducers to the monitor and permitting telemetering by radio or wire without requiring changes in transducer or monitor design or adjustment or calibration. A telemetering system which presents to the monitor a variable resistance identical to the varying resistance produced by a transducer at the patient. A temperature transmission channel wherein a thermistor resistance is connected in a bridge circuit which is balanced by successive trials of a set of resistors digitally selected by a counter and comparator. The code for the selected value which produces balance is transmitted to the monitor station where it is used to actuate an identical set of resistors to reproduce the input resistance value.

Abstract: A system for telemetering data from a patient to a monitor permitting direct connection of patient's sensors and transducers to the monitor and permitting telemetering by radio or wire without requiring changes in transducer or monitor design or adjustment or calibration. A telemetering system which presents to the monitor variable resistances identical to the varying resistances produced by the transducers at the patient. A temperature transmission channel wherein a thermistor resistance is digitized for transmission, with the digital data being utilized to generate a resistance at the receiver corresponding to the thermistor resistance. A pressure transmission system providing for transmission of waveform and peak and trough values of the waveform, with the waveform being reconstituted at the receiver and converted to a varying resistance for connection to the monitor, simulating the original pressure transducer resistance.

Abstract: Apparatus and method for continuous measurement and display of the endocardial viability ratio of a patient to provide an indication of the condition of the heart muscle. A system using signals representative of the systemic arterial pressure and the left atrial pressure as inputs to generate a tension time index and a diastolic pressure time index by separation of the systemic arterial pressure wave form into two parts and selective integration of the inputs, followed by division to obtain the desired ratio.