초록 ▼

An interface circuit for use in a portable apparatus for measuring the electrochemical characteristics of a sample is disclosed. A disposable cartridge, including a plurality of interconnected flow chambers, houses a printed circuit board substrate upon which reference and indicating electrodes are

An interface circuit for use in a portable apparatus for measuring the electrochemical characteristics of a sample is disclosed. A disposable cartridge, including a plurality of interconnected flow chambers, houses a printed circuit board substrate upon which reference and indicating electrodes are formed. The electrodes are employed in the presence of chemical reagents to aid in the electrochemical determination of a sample undergoing analysis. Such a system provides a high source impedance signal. Interface circuitry is provided between the electrodes and measuring electronics which causes a controllable current loop to be formed through the physical contacts points between the electrodes and the measuring electronics so that low ohmic contact is established. The control circuitry for the current loop is isolated from the measuring circuitry so that measurements taken are not influenced by the current loop formation.

대표청구항 ▼

An apparatus for measuring a signal having a high source impedance of the type in which the signal to be measured is presented across a pair of contacts, and a measuring circuit is placed in physical contact with the pair of contacts, comprising interface means having a plurality of contacting struc

An apparatus for measuring a signal having a high source impedance of the type in which the signal to be measured is presented across a pair of contacts, and a measuring circuit is placed in physical contact with the pair of contacts, comprising interface means having a plurality of contacting structures which can be placed in physical contact with and at spaced apart points on at least a first one of the pair of contacts for circulating a current through the first one of the pair of contacts by way of the plurality of contacting structures, wherein the circulating current flows out of one of the plurality of contacting structures, through the first one of the pair of contacts, and into another of the plurality of contacting structures, and further wherein the magnitude of the circulated circuit is selected to cause a low ohmic contact to be developed between the plurality of contacting structures and the first one of the pair of contacts; means for measuring the signal between one of the plurality of contacting structures and the other of the pair of contacts.