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    Nanodrop-Style UV-Vis Spectrophotometer

    3D Printable "Nanodrop-style" spectrophotometer, capable of measuring ~400-750nm visible light. This project is based on the DIY Microvolume Spectrophotometer project available on Hackteria (https://hackteria.org/wiki/DIY_Microvolume_Spectrophotometers), including modifications inspired by TheThoughtEmporium's version on YouTube (https://www.youtube.com/watch?v=pIk8I10ZmYY&t=641s).

    Using a 405nm laser diode and blue-light filter, this system can accurately quantify stained DNA using a standard curve, using as little as 5 uL of sample. GelGreen DNA stain worked well for me. The resolution is right around ~1nm, although the CFL-Hg doublet at 546nm is just barely not-resolvable. I expect this could be improved by using a higher-quality FS mirror.

    A USB Webcam functions as a detector, which can be plugged into any computer for spectral analysis. There are several open-source programs available to do this ('Theremino Spectrometer' or I also found an online program here: https://gaudi.ch/Spectrometer/). Theremino gives a lot of functionality for focusing and adjusting your image, which I found necessary for accurate comparisons between samples.

    The design was modified from Hackteria to remove the bolt holes and allow panels to press-fit together. I also created a razor blade mount to act as an adjustable slit over the light aperture. The case has been enlarged to fit a larger webcam, and the primary aperture in the top panel was reduced (I ended up thinning it further to ~3mm with some tape between the slit-adjuster and the case top-panel).

    Other Components (Watch the linked video for assembly):

    • USB Webcam (I used the cheapest cam I could find at Walmart, Onn $20, and adjusted the stl for the camera mount holes to align)
    • Diffraction Grating (1000 lines/mm; cheap on Amazon)
    • First Surface Mirror (I just used paint stripper to remove the paint backing from a shard of cheap mirror, which is accurate enough for what I'm doing)
    • 5mm White LED + Power (I tried wiring my light source into the webcams power supply, but the output was quite unstable. I instead opted for a simple AA battery holder pack. For the LED, I used a flat-head 5mm white.)
    • 5mm Acrylic Disk (I made mine out of a paperclip tray from the dollar store, and frosted both sides with 600 grit sandpaper. In the end, I had to stack two disks and sand the height down until it sat flatly above the microscope slide with a 1mm air gap)
    • Microscope Slide/Cover Slip (Sample deck and LED cover)
    • Disposable Razor Blades (Optical slit)
    • 4x screws/nuts to mount the mirror and light source lever + 1 screw to set the height of the light source lever.

    For DNA quantification:

    • Long-pass Light filter (Remove 405nm light to increase sensitivity for DNA dye fluorescence. These can be quite expensive, and I'm currently experimenting with the Tiffen photography filter mentioned in the video. Mount this in front of the diffraction grating)
      -405nm Laser Diode + Power
      -Fiber optic audio cable splitter (Allows for both light sources. Optionally print a second light source lever or LED mount that you can swap out)