I need to build this instrument for a science experiment related to vitamin D production. I understand that it is necessary to use a photo-diode that responds to UVB wavelengths only and that I need to use an operational amplifier that functions as a transimpedance amplifier with a very high input impedance. Since the photo-diode will generate a current in the range of 1 nano ampere to 1 micro amperes, several precaution will need to be taken to build a properly functioning circuit. Can someone identify the precautions that I will need to take in designing and building this circuit? Since UVB photo diodes are quite rare, I also need some help in selecting a component that will be reliable and available.
I would use a wide spectrum photodiode, and use physical optical filters to neck it down to UVB. This will not be cheap, but it shouldn't be cost prohibitive.