Development of a novel LED color-switching type biosensor system for the visualization of fish stress response
Some biosensor systems developed these days for monitoring fish stress response, through measuring blood glucose concentration (stress indicator) in real-time, even fish swimming freely. However, it is hard to make an instant judgment of fish stress level. In this research, we aimed to develop a new visualization system which can make a natural judgment by visual observation on 3 different levels for fish stress response. This judgment was achieved through the color change of a multi-color LED to help people make a better understanding of fish stress response. The principle of the sensor system is based on the principle of converting sensor output value obtained by glucose biosensor corresponding to the stress response into voltage value and changing the color of the LED (Red, Yellow, Green). First, interstitial fluid near the sensor insertion point was sampled from the test fish and adjusted to concentrations used to define the yellow and red LED by adding a standard glucose solution. When the glucose level in the collected sample changed to the threshold pre-setted, it was successful in switching the color to green, yellow, and red. Furthermore, we attempted to insert the proposed sensor into actual sample of fish and to monitor the color change of the LED in real-time in vivo while providing stressor to the fish. When applying this system to the real test fish in vivo, a color change corresponding to the sensor response was observed successfully. Therefore, fish stress responses can be visually grasped by using our proposed system.