Researchers from National Taiwan Ocean University developed an efficient power-free method to visualize and evaluate stress in fish
Inadequate breeding environments can lead to stress in fish, thereby affecting their development and health. Change in blood glucose levels is linked to stress levels in fish. Therefore, a blood indicator can help to determine fish health conditions. Conventional methods used for this purpose opt to use anesthetics in fish to withdraw blood for measuring glucose level. However, the method is challenging to acquire true blood glucose levels in fish and also is labor-intensive. Now, a team of researchers from National Taiwan Ocean University developed a self-powered glucose biosensor (SPGB) that can be operated underwater to monitor physiological status of free-swimming fish.
The biosensor was used to monitor the physiological status of a free-swimming fish in a tank in real time with the help of a smartphone with an app. The glucose levels in free-swimming fish treated with cold shock was continuously measured for 8 h in the fish tank. The team used a smartphone with an App to determine the concentration of glucose by measuring LED blinking frequencies. SPGB contains a needle-type enzymatic biofuel cell (N-EFC). To access biofuels and a gas-diffusion biocathode sealed in an airtight bag, the team inserted N-EFC in the caudal area of the fish. The N-EFC was submerged in water and connected to a charge pump IC and capacitor to allow charging cycle of the bioelectricity generated from the N-EFC. A LED was connected to set-up and was sealed in an airtight bag along with the charge pump IC.
The SPGB continuously operated for 48 hours and offered sufficient biofuel of 180 mg/dL glucose with around 6% drop of the maximum power density. According to the researchers, SPGB offers an efficient power-free method to visualize and evaluate stress in fish. In further research, the team plans to develop a self-powered biosensor that can simultaneously detect three of the most important indicators for physiological stress responses: the lactate, cholesterol, and glucose. The research was published in the journal MDPI Energies on May 14, 2019.