The following comments were made on this basic design. First, if you're using LEDs instead of light spectrally split by a prism as excitation light, you should be aware that light other than the desired excitation wavelength is also being emitted. Second, if the camera is not equipped with a filter, light other than LED or fluorescent light will enter the camera so it should be attached.
Discussion
Discussion with Shimadzu Corporation
On September 22, 2022, we asked an engineer from Shimadzu Corporation, a major Japanese manufacturer of measuring instruments, to give us feedback on our basic design and to advise us on the design of measuring instruments. Shimadzu Corporation
I Feedback on our basic design
II Advice on our prototype and product
We received four suggestions for appropriate sensors when using a sensor instead of a camera. First, there are sensors that take pictures while cooling, but they are expensive. Photodiodes seem to be good with low noise. Silicon photodiodes might be good to use while cooling. Using a photomultiplier is not a bad idea, but it is not easy. As a result, a photodiode that converts light into voltage and outputs it as an electric current is the best choice. Next, we were advised about filters. Interference filters are pricey. Color glass filters are attached to the surface of the camera and are inexpensive. However, light reflects off the surface of the filter, so we have to take the reflection into account when making measurements. If you want to use a filter to cut out only excitation light, you can use a colored glass filter. If we use colored cellophane of a hundred yen store as a filter, the cellophane could be a source of fluorescence. Since blue has high energy, we should be careful that the cellophane does not become a fluorescent source. Colored glass filters are easy to handle because they do not become a fluorescent source.
We had planned to make the prototype walls out of plastic and asked if he had any recommendations regarding materials for the prototype. A black acrylic board was suggested. The reason is that black acrylic panels do not let light in from the outside. However, it is necessary to confirm that the acrylic board does not fluoresce when exposed to light. Engineering paper such as black drawing paper is not bad. However, we were told that highly reflective papers are not suitable because they cause light scattering.
Regarding the observation of fluorescence, we received the opinion that we should adjust the minimum sensitivity of the camera. The minimum sensitivity should be set to the level of fluorescence that can be identified as fluorescent. The way to adjust the sensitivity is to decrease the concentration of fluorescent paint based on the power density of the excitation light under constant excitation light conditions. If you just want to know if there is fluorescence or not, just increase the excitation light. However, he suggested that if we want to measure fluorescence quantitatively, we should also check the wavelength band of fluorescence.
As for the environment in which to observe the well, he suggested that it would be better to use a camera from below, rather than from above. This is because water droplets cloud the camera and scatter the light. However, the excitation light seems to be fine from above.
figure. iGEM Tokyo Tech members and Shimadzu engineer
