Development of H2O2 image sensor for GABA and glutamate imaging

We have developed H
₂
O
₂
image sensors of 128×128 pixels with spatial resolution of 23.55 μm successfully. This sensor consisted of hexacyanoferrate(II), hexacyanoferrate(III), enzyme, and an Au thin film deposited on a highly sensitive potential image sensor, where hexacyanoferrate(II), hexacyanoferrate(III), and enzyme were immobilized on the Au film. The H
₂
O
₂
image sensor measures the interfacial potential between the solution and the Au film caused by a redox reaction involving H
₂
O
₂
, and thus the sensor signal is not affected by the buffering action of the solution. The output increased linearly with the ratio of Fe2+, Fe3+ of their mixture; thus it was confirmed that the sensor can measure the redox potential qualitatively. Furthermore, we demonstrated that the sensor can visualize the diffusion behavior of H
₂
O
₂
and glutamate. These results also suggest the possibility of imaging neurotransmitters such as Serotonin, Dopamine etc, by utilizing the enzyme reaction that generates H
₂
O
₂
.