Siemens Aktiengesellschaft

Gunter Luft

Ulrich Gebhardt

Konrad Mund

Gerhard Richter

Dieter Kuhl

Ferdinand V Sturm

For determining the urea concentration in liquids in continuous operation, with a high sensitivity and reliable determination of the urea content over an extended period of time, an electrode which is separated from the urea containing liquid by means of a diaphragm with a diffusion coefficient of less than 10.sup.-7 cm.sup.2 s.sup.-1 for urea has impressed on it potentiostatically and cyclically, two potential values, the more positive potential being between 0.9 and 2.0. V/H.sub.2 rev, and the more negative potential being lower than 0.6 V/H.sub.2 rev, and at the more positive potential, the current flowing within a predetermined time interval is evaluated as the measuring signal.

Apparatus for urea analysis

For determining the urea concentration in liquids in continuous operation, with high sensitivity and reliable determination of the urea content over an extended period of time, an electrode which is separated from the urea containing liquid by means of a diaphragm with a diffusion coefficient of less than 10.sup.-7 cm.sup.2 s.sup.-1 for urea has impressed on it potentiostatically and cyclically, two potential values, the more positive potential being between 0.9 and 2.0. V/H.sub.2 rev and the more negative potential being lower than 0.6 V/H.sub.2 rev, and at the more positive potential, the current flowing within a predetermined time interval is evaluated as the measuring signal.

Method for urea analysis

A method for determining the concentration of sugar in the presence of interfering foreign substances, by means of a test electrode with a membrane placed in front of it, the electrode being contained in an electrocatalytic sugar sensor, whereby the test electrode is set potentiostatically to a reactivation potential and to a test potential and the current flowing during the set test period is evaluated as a test signal. The invention formulates a method such that with varying concentrations of urea a sensitive determination of sugar concentration which is reliable over a long term is achieved. The invention discloses the method which includes the step that after the reactivation potential and prior to the test potential a third potential that is more negative than the test potential is applied to the test electrode. The technique proposed in the invention is particularly appropriate for the determination of the concentration of glucose in body fluids.

Method for determining sugar concentration

A method for determining the concentration of sugar in the presence of interfering foreign substances, particularly for determining glucose in a body fluid, by means of an electrocatalytic sugar sensor which has a measuring electrode in which the measuring electrode is alternatingly set potentiostatically to a reactivation and a measuring potential and the current flowing during the measuring period is evaluated as the measurement signal. To prevent foreign substances from exerting an interfering influence and thereby permit a sensitive sugar determination which is reliable over an extended period of time, a hydrophilic diaphragm is arranged in front of the measuring electrode to impede the resupply of the interfering foreign substances to the measuring electrode so that a diffusion limit current adjusts itself during the reactivation phase in the oxidation of the foreign substances; and the current is evaluated with a time delay relative to the start of the measuring period.

Method for determining the concentration of sugar using an

The invention relates to an implantable dosing device for the continuous, controllable release of medication in the human or animal body, comprising a medicine reservoir of variable volume and a liquid chamber which is tensionally connected to the medicine reservoir and the volume of which can be varied by liquid which is transported through an ion exchange diaphragm by electro-osmosis due to an electric field between two electrodes. According to the invention, the electrodes in such an implantable dosing device are hydrogen electrodes which are connected to each other by a line for hydrogen, and means are further provided for compensating hydrogen losses.

Implantable dosing device

The invention relates to an implantable dosing device for the continuous release of medication in the human or animal body, comprising a medicine reservoir of variable volume and a propellant chamber of variable volume tensionally connected to the medicine reservoir, as well as flow-control means. According to the invention, an electro-osmotic control valve with an ion exchange diaphragm arranged between two porous electrodes is provided for the flow control in such a dosing device.

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Lauf, Germany

Gunter Luft