Abstract:
An electrochemical measuring electrode device (10) for polarographically measuring the partial pressure of oxygen in an electrolytic medium comprises a cathode (14) which is capable of reducing oxygen and defines an exposed oxygen-reducing cathode surface (20), an anode (18), which defines an exposed anode surface which is arranged relative to the exposed oxygen-reducing cathode surface so as to communicate electrolytically therewith through the electrolytic medium, and a membrane (24), which covers the exposed oxygen-reducing cathode surface and further defines an electrolyte chamber (22) in which the electrolytic medium is confined. In order to effectively promote the decomposition H 2 0 2 generated in the electrolytic medium as an oxygen reduction intermediate and thereby reduce the response time of the electrode, a stable, non-biological catalytic means is provided catalytically communicating with the H 2 0 2 . The stable, non-biological catalytic means is preferably constituted by platinum black particles which may be received by the membrane at a central region (42) thereof or alternatively be received by a support structure which may further constitute a covering of at least part of the membrane (24). The platinum black particles may be pressed into a foil material constituting a base material of the membrane or alternatively be applied in a suspension to the membrane whereupon the suspension is solidifyed.
Abstract:
In an electrochemical measuring electrode device (10) comprising sensor means (12, 13 and 36) for generation of one or more measuring signals, the measuring signals are multiplexed in a first multiplexing means included in an integrated electronic circuit (23) and transmitted therefrom through a two conductor cable (37) to a cooperating measuring apparatus (50). In the measuring apparatus (50), the measuring signals are demultiplexed and displayed on a display (48). The circuit (23) is mounted on an insulating ceramic substrate (21) also supporting a temperature dependent NTC resistor (28) and a Zener diode (30) together constituting a thermostating means of the electrode device. The electronic circuit of the electrode device (10) and the heat generating Zener diode (30) are supplied with power from the measuring apparatus (50). The transmission is preferably carried out in time-division multiplexed state, so that the measuring results generated by means of the sensor means and the temperature representative signal generated by the NTC resistor (28) are transmitted within individual time intervals, while an electrical power signal for supply of the electronic circuitry of the electrode device and for supply of the Zener diode (30) is transmitted within a specific subperiod of each of the transmission time intervals. The gated amplifier comprises a high-gain differential DC-amplifier a storage capacitor and a switch means for conversion of the gated amplifier to a mode in which any input offset of the DC-amplifier is transmitted in a unity gain mode.
Abstract:
Dans le but de contrecarrer la coagulation d'un échantillon sanguin prélevé du corps (24) d'un animal ou d'un être humain et introduit dans un réceptacle tel qu'une chambre (14) d'une seringue, un anticoagulant est ajouté à l'échantillon dans le receptacle. L'anticoagulant est capable de lier des espèces de cations dans le sang que l'on veut mesurer par la suite. Ces espèces de cations comprennent des ions hydrogène, des ions ammonium, des ions de métal alcalin tels que des ions potassium et sodium, et des ions métalliques alcalino-terreux tels que des ions magnésium et calcium. De manière à compenser les proportions des espèces de cations sélectionnées qui sont liées par l'anticoagulant, un additif contenant de telles espèces de cations est ajouté à l'échantillon de manière à obtenir sensiblement la même concentration des espèces de cations sélectionnées dans un état non lié dans l'échantillon sanguin traité avec l'anticoagulant que dans l'échantillon sanguin non traité. L'anticoagulant et l'additif sont de préférence ajoutés à l'échantillon sanguin sous forme d'une composition qui peut être déposée ou portée par un corps porteur (15) pouvant être agencé dans le réceptacle dans lequel l'échantillon sanguin est introduit. La densité de masse du corps porteur non mouillé est de préférence plus petite que le poids spécifique de l'échantillon sanguin de manière à éviter l'emprisonnement de bulles d'air dans le réceptacle. Dans son état mouillé, la densité de masse du corps porteur est également de préférence différente du poids spécifique de l'échantillon sanguin de sorte que le corps porteur (15) peut être utilisé comme organe d'agitation qui améliore le mélange de la composition anticoagulante avec l'échantillon sanguin. Le corps porteur (15) peut par exemple être constitué de papier filtre.
Abstract:
Dispositif d'électrode de mesure sensible aux ions avec un élément sensible aux ions basé sur un matériau céramique cristallin conducteur ionique. Le dispositif d'électrode présente une sélectivité envers l'ion Na+ contre l'ion H+ correspondant à la sélectivité des électrodes connues à membrane solide à base de verre sensible au sodium. Les dispositifs d'électrode de mesure sensibles aux ions présentant de bonnes propriétés de sélectivité sont basés sur un matériau cristallin conducteur ionique, dont la structure cristalline comprend un espace intersticiel tridimensionnel contenant des emplacements pour l'ion, en particulier un matériau dont l'espace intersticiel possède des goulots d'étranglement permettant juste le passage de l'ion. Est également décrit un procédé de préparation d'un matériau céramique polycristallin basé sur des oxydes de zirconium, de phosphore et de silicium.
Abstract:
A liquid sampler which may be used for collecting samples of arterial blood is preferably in the form of a syringe. A venting passage (25, 31) is defined in the syringe piston (12) so that gas may escape through the venting passage when arterial blood flows into the cylinder space (17) under the influence of the arterial blood pressure. The venting passage is controlled by valve means (19,21), which automatically close the venting passage when the cylinder space has been filled with blood and the blood starts flowing into the venting passage. The venting passage is closed by liquid resistant valve surface parts, and movement of these surface parts to their closing position is caused by a liquid reacting substance (22) which is exposed to the liquid sample flowing into the venting passage. This liquid reacting substance may, for example, be a material which swells, expands, or is softened when contacted by liquid. Alternatively, the liquid reacting substance may be a liquid soluble material.
Abstract:
@ A syringe for collecting blood samples, especially arterial blood samples, comprises a syringe cylinder (11) and a piston assembly (12) displaceably arranged therein. The piston assembly defines a venting passage (25, 37, 31) through which gas or air may escape when arterial blood flows into the cylinder space (17) under the influence of the arterial blood pressure. The venting passage is controlled by valve means (23, 31), which may selectively and reversably be opened and closed independently of axial displacement of the piston assembly. The valve means may, for example, be operated by rotating a piston rod through a predetermined angle or by means of a valve actuating lever (35), which is biased towards a position in which the valve means are closed, and which may be tilted to an open position by depressing a finger grip (36) positioned at the free outer end of the piston rod (32).
Abstract:
The salt bridge liquid contains Na + -ions and HCOO--ions in substantially equimolar amounts, preferably in a concentration larger than or equal to 1 M, in particular about 4M. When this salt bridge liquid is used, the potentiometric measurement will give corresponding results when measuring a blood sample and the corresponding plasma sample because the suspension effect which is caused by the erythrocytes and which is seen when using other salt bridge liquids is substantially eliminated. Furthermore, different blood samples with the same ion concentration but with varying erythrocyte content will give corresponding measuring results.