3.2. Effects of measurement conditions on analytical signal
As the sensor comprises a biological catalyst (enzyme),
response can vary depending on temperature and pH of the solutions
in which the immobilized enzyme membrane is placed.We
therefore investigated the effects of these factors on analytical
signal. Fig. 4 shows the effects of temperature on analytical
signal. Output increased as temperature increased above 15 ◦C,
then began to decrease above 35 ◦C. Since the body temperature
of fish (tirapia) farmed in temperate areas is 20–30 ◦C, matching
the ambient water temperature, the present sensor is suitable
in such fish. Fig. 5 shows the effects of pH on analytical signal.
Glucose levels were measured by adjusting the pH of buffer
solution in the needle-type hollow container from 5.6 to 8.2, and
maximum response was obtained at pH 6.5. Since the bodily fluids
of fish are mostly neutral, no problems are likely to occur
using the sensor in fish.