| 摘要 |
<p>An interface circuit for use in a portable apparatus for measuring the electrochemical characteristics of a sample is disclosed. A disposable cartridge (16), including a plurality of interconnected flow chambers, houses a printed circuit board substrate (44) upon which reference and indicating electrodes (40) 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 (40) and measuring electronics which causes a controllable current loop to be formed through the physical contact points (56) 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.</p> |
