0
\$\begingroup\$

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.

\$\endgroup\$
  • \$\begingroup\$ How can anyone know what is available to you in your part of the world. This is something that you'll have to find yourself because this is an EE site specializing in design issues and not some branch of a purchasing department. \$\endgroup\$ – Andy aka Nov 10 '16 at 14:54
  • \$\begingroup\$ A transimpedance amplifier with very high input impedance would be.. broken. \$\endgroup\$ – Spehro Pefhany Nov 10 '16 at 15:01
  • \$\begingroup\$ What information have you collected about the wavelengths involved in vitamin D production and how to process that information into a measurement value? This is the place to start and you've provided zero information on it. Can you provide details? \$\endgroup\$ – jonk Nov 10 '16 at 17:38
  • \$\begingroup\$ You could use an UVB-LED as a photosensor. \$\endgroup\$ – Janka Nov 10 '16 at 18:51
  • \$\begingroup\$ The wavelength range for UVB is 280 nm to 320 nm. Scot Seidman in his answer suggest that I use a wide spectrum photodiode and use an optical filter. \$\endgroup\$ – Aniruddha Nov 11 '16 at 9:18
0
\$\begingroup\$

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.

http://www.asahi-spectra.com/opticalfilters/uv_transmission_filters.html

\$\endgroup\$
  • \$\begingroup\$ This solution will certainly work but is somewhat expensive. I guess UVB photodiodes are quite rare and not much choice exists. \$\endgroup\$ – Aniruddha Nov 11 '16 at 9:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.