| 摘要 |
A biochemical probe (10) for determining the freshness of fish or meat, or inspecting the nature of other animal tissues, employs a hypoxanthine enzyme sensor (20) located at a sharp end (16) of the probe. The sensor comprises a reference electrode (24), a pair of sensor electrodes (26), and a membrane (34) that extends over these electrodes to form an outer face of the sensor, this face being a continuation of the surface (18) of the shaft of the probe. The invention is characterized in that the membrane is a thin layer of anodized aluminum oxide which is highly porous and has a large number of small cells (35) extending from the outer face into communication with the electrodes. The cells contain an electrolyte, and those of them in communication with a first one of the sensor electrodes also contain immobilized hypoxanthine oxidase enzymes (37). A comparison of the current flowing between the first sensor electrode and the reference electrode, with the current flowing between the second sensor electrode and the reference electrode, provides an indication of the concentration of hypoxanthine at the outer face of the sensor. If the probe has been inserted into the meat of a fish, a high hypoxanthine concentration would indicate a lack of freshness. The miniturized nature of the sensor, its mounting on the end of a sharpened probe, and the use of a thin layer of highly porous anodized aluminum oxide as the enzyme matrix, achieve a faster response time than hitherto available. The inventive use of anodized aluminum oxide can be applied to a wide range of other chemical (including biochemical) enzyme sensors for mounting in probes or other use. |
