Abstract:
The invention is directed to a measuring cell for an electrochemical gas sensor having an electrolytic chamber and a measuring electrode as well as a counter electrode. In the direction facing the ambient, the measuring electrode includes a diffusion membrane as well as a diffusion barrier. The diffusion barrier is made of a material which is a good conductor of heat and is provided with a plurality of passages. A temperature-sensitive element is provided in the immediate proximity of these passages and faces toward the ambient. With this configuration, the temperature dependency of the diffusion capacity of the gas sample passing through the diffusion barrier can be included in the processing of the signal indicative of the measurement.
Abstract:
The invention is directed to an apparatus for sensing a gaseous component in air and includes a housing having a flushing chamber through which an air sample can flow via a closeable inlet and a closeable outlet. The sensor is mounted in a measuring chamber above the flushing chamber and is hermetically sealed from its ambient not only during the time that the flushing chamber is flushed with the air sample; rather, and most important, during the measuring operation itself in order that any influences from a diffusion of the ambient air into the measuring chamber is prevented. For this purpose and to determine the sample quantity diffusing into the measuring chamber at the beginning of a specific period of time, the inlet as well as the outlet of the flushing chamber is closed while at the same time the diffusion passage interconnecting the two chambers is opened. After the time period has run, the diffusion passage is again closed.
Abstract:
An electroimpedance tomograph with a plurality of electrodes (1) is provided, which can be placed on the body of a patient and are connected via a selector switch (60) with a control and evaluating unit (20). The control and evaluating unit (20) cooperates with the selector switch (60) such that two electrodes each are supplied with an alternating current from an AC power source (22) and the detected analog voltage signals of the other electrodes are processed in order to reconstruct therefrom the impedance distribution of the body in the plane of the electrodes, wherein a symmetrical AC power source is used to reduce common-mode signals. To further suppress interferences due to common-mode signals, provisions are made for the control and evaluating unit (20) to be set up, furthermore, for detuning the common-mode signal of the alternating current on the body against the ground by means of a common-mode signal measuring electrode (4) and, based on this, the symmetry of the symmetrical AC power source such that the common-mode signal on the body is minimized, and the corresponding detuning parameters are stored for each electrode pair.
Abstract:
A device and a process for determining the change in the functional residual capacity (FRC) in a simple manner. Based on a first respiration phase for mechanical respiration, a recruitment maneuver is performed for this during a second respiration phase, and respiration is switched back to mechanical respiration during a third respiration phase. Reference values Uref/1, Uref/3 are formed from the end-expiratory values of the impedance measured signals U during the first respiration phase and the third respiration phase, and the difference ΔU (ΔFRC) between the reference value Uref/3 of the third respiration phase and the reference value Uref/1 of the first respiration phase is an indicator of the change in the functional residual capacity of the lung of the test subject.
Abstract:
A device for supplying a patient with breathing gas, in which an initially high initial pressure paw(t=0) applied from the outside is automatically lowered by means of a control circuit to a lower inspiratory pressure paw(t) as soon as a pulmonary internal pressure plung(t) threatens to exceed a predetermined pulmonary target pressure plung,soll. Overinflation of the lungs due to the respiration is thus ruled out according to the present invention. The device permits, moreover, rapid filling of the lungs with breathing gas and makes thus possible a comparatively long phase of expiration. A process is also provided for regulating a respirator and for respirating a patient.
Abstract:
An electroimpedance tomograph is provided with a plurality of electrodes (1), which can be placed on the body of a patient and are connected to a control and evaluating unit (20) via a selector switch (60). The control and evaluating unit (20) cooperates with the selector switch (60) such that two electrodes each are supplied with alternating current from an AC power source (22). The detected analog voltage signals of the other electrodes are sent into the control and evaluating unit (20) via a measuring amplifier (62) and AD converter (64) and are processed there in order to reconstruct the impedance distribution of the body in the plane of the electrodes therefrom. A symmetrical AC power source (22) is used to reduce common-mode signals. To make it possible to suppress errors due to common-mode signals, provisions are made for the control and evaluating unit (20) to be set up for making available an additional common-mode signal at an output during an adjusting mode of operation and to send it to the body via common-mode signal electrodes (4, 90) that can be placed on the body. The control and evaluating unit (20) is prepared, furthermore, to adjust the measuring amplifier (62) according to value and phase for each electrode pair connected by the selector switch (60) such that the common-mode signal at the output of the measuring amplifier (62) is minimized, and the adjusted parameters are stored for each electrode pair.
Abstract:
A modular system of electronic assembly units worn close to the body can be connected to a central supply module. At least one textile-supported supply line (1) leads to inductive interfaces, with which additional supply lines or electronic assembly units can be coupled, which likewise have at least one inductive interface. At least one portable supply module (6) has a power supply unit (9) and a control unit (10). The control unit (10) is designed such that it can assume a master function in respect to other coupled electronic assembly units, wherein the portable supply module (6) can be coupled via at least one inductive interface with the textile-supported supply line (1) such that it makes possible the power supply of the electronic assembly units (4) by the electronic supply unit (9) contained in the portable supply module (6).
Abstract:
The invention relates to a method for operating an amperometric measuring cell which includes at least a measuring electrode 2 and a counter electrode 3 in an electrolyte chamber 4 filled with an electrolyte. The measuring cell is closed off by a permeable membrane 7 with respect to the measurement sample to be detected. The method of the invention improves the run-in performance of the measuring cell 1. The method includes the step of applying a voltage U.sub.1 across the electrodes (2, 3) during a first time span T.sub.1 starting at a reference time T.sub.0. A reference voltage U.sub.0 is assumed at the start of the measurement and the voltage U.sub.1 is increased relative to the reference voltage U.sub.0.
Abstract:
The invention is directed to a measuring apparatus for detecting gases with the aid of an electrochemical sensor with a diffusion barrier being disposed ahead of the sensor. The measuring apparatus is improved in such a manner that the sensor is adaptable with respect to its sensitivity to different measuring ranges during operation without external intervention. The speed of response of the sensor is also increased. Diffusion openings in the diffusion barrier are closable with a valve arrangement associated with the valve openings. The valve arrangement is connected via a valve drive unit to a measurement value comparator for changing the operating position of the particular valve to be actuated.
Abstract:
A circuit arrangement is disclosed for correcting the output of a sensor which experiences changes in sensitivity due to the presence of one or more influencing factors, such as the concentration of a material to be sensed, or the passage of time. The circuit arrangement includes a correction network which generates a simulated sensitivity curve which simulated curve is combined with the output of the signal to produce a corrected output signal which has apparent constant sensitivity.