SpecPhone
A 3D-printable visible absorbance spectrometer for education
Introduction
Visible absorption spectroscopy is an experiment that measures the concentration of colored compounds in a sample. Because of a simple relationship between concentration and the amount of light absorbed, spectrophotometry has a wide range of applications in chemistry labs, biomedical research, and clinical diagnostics.
Our lab has developed the original SpecPhone as well as the updated DualSpec: Smartphone-based spectrophotometers that can be made with a 3D printer and some inexpensive parts. These devices can make analytically accurate measurements of concentration and can be used for education and DIY scientists.
The DualSpec is the most recent version that is compatible with many smartphones and makes more accurate measurements. (The original SpecPhone manuscript can be found here and the original stl files here). We designed the housing to position the optical elements in a way that facilitates measurements using a standard laboratory cuvette. A schematic of the device is shown below.
In the DualSpec, we upgraded the path to include a sample and reference beam, which greatly improves the signal to noise of the absorption spectra:
Protocols and Instructions
Protocols and instructions are available in the following papers, and a detailed parts list with links is found below:
Bogucki, R.; Greggila, M.; Mallory, P.; Feng, J.; Siman, K.; Khakipoor, B.; King, H.; Smith, A. W. A 3D-Printable Dual Beam Spectrophotometer with Multiplatform Smartphone Adaptor. J Chem Edu 2019, 96 (7), 1527-1531. DOI: https://doi.org/10.1021/acs.jchemed.8b00870.
Grasse, E. K.; Torcasio, M. H.; Smith, A. W. Teaching UV–Vis Spectroscopy with a 3D-Printable Smartphone Spectrophotometer. J Chem Edu 2016, 93 (1), 146-151. DOI: https://doi.org/10.1021/acs.jchemed.5b00654.
Parts List
Housing: The housing can be printed on any consumer or commercial 3D printer. Many libraries and schools have 3D printers available for free or minimal costs. Websites also offer 3D print services for low cost. The *.stl print file is available upon request (aw.smith@ttu.edu) or can be downloaded from Thingiverse:
https://www.thingiverse.com/thing:3404762
Slits: Each slit is a removable part of the device. The width of the opening is related to the resolution of the instrument. In our design, the slit can be removed and changed to illustrate the resolution principle. Several slits are available from 0.1 to 5 mm. The *.stl print files are available upon request (aw.smith@ttu.edu) or at
https://www.thingiverse.com/thing:3404762
Cuvette: Any 1 cm pathlength polystyrene cuvette will fit in the device. Below are a few supplier links:
Amazon (or search for: Polystyrene Square Spectrophotometer Cuvette)
Mirror: A 1”x1” aluminum mirror is available from craft suppliers. It rests on a 45° face of the plastic support and is held into place with glue or double-sided tape.
Amazon (or search for: 1 Inch Mirror Tiles)
Diffraction Grating: We chose an inexpensive grating that can be cut with scissors to fit the light path clearance. It is purchased as a 6”x12” film sheet with 1000 lines/mm ($2.50).
Light source: A desk lamp or LED source is fine. The only requirement is that it produces a stable light intensity and a relatively flat spectrum over the visible wavelengths.