Detection of a Specific Fluorescent Wavelength via iPhone camera

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Discussion Overview

The discussion revolves around the feasibility of using an iPhone or Android camera to detect specific fluorescent wavelengths emitted by fluorescent bacteria, particularly GFPa1. Participants explore the potential for filtering out all other light except for the emission frequency, considering both theoretical and practical aspects of camera functionality and optical filtering.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the possibility of configuring a smartphone camera to recognize only light corresponding to a specific wavelength or a narrow range of wavelengths, suggesting this could facilitate on-the-fly detection of fluorescence.
  • Another participant suggests that an actual optical filter would be necessary in front of the camera, as built-in filters may have broad transmission bands that are inadequate for the specific detection needs.
  • A third participant provides an abstract discussing the importance of optical filters in fluorescence instrumentation, emphasizing their role in spectral control and detection sensitivity, and mentions thin-film interference filters as commonly used in fluorescence applications.
  • One reply proposes a practical approach to test the camera's capabilities by photographing an arc lamp to see if discrete spectral lines can be identified, indicating the need for external optics for effective wavelength selection.
  • Links to resources and suppliers of optical filters are shared, suggesting potential avenues for obtaining the necessary equipment.

Areas of Agreement / Disagreement

Participants generally agree that a filter is likely needed to achieve the desired wavelength specificity, but there is no consensus on the effectiveness of smartphone cameras for this purpose or the best methods to implement such filtering.

Contextual Notes

Limitations include the uncertainty regarding the specific capabilities of smartphone cameras in relation to fluorescence detection and the potential variability in filter effectiveness based on different optical configurations.

Carroll1
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So in my lab, I am working with fluorescent bacteria, specifically GFPa1 (green fluorescent protein a1) which are excited with around 500nm light and emit around 516 nm. Forgive me if these aren't correct, it isn't essential for this write-up and my notes aren't in front of me. Is there any way to filter out all other light except for the light at the emission frequency from an iPhone/Android camera? I'm not too familiar with the cameras, but recognize that they function using HSV which can correspond to colors we see on the screen. So is it possible to make the camera only recognize light with an HSV corresponding to a specific wavelength (or even a small range of wavelength of light such as +/- 5 nm)? This would be very convenient for detection of the fluorescence, and could do it on the fly.

I haven't had too much luck finding stuff elsewhere online, but perhaps there already is an app or something that can do this if it is possible. Any help or knowledge would be fantastic!
 
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You probably need an actual filter in front of the camera. The built in filters probably have rather broad transmission bands for red, green, and blue. That's probably too wide for your purposes, but you could check the green channel and see if that works.
 
Optical filters for wavelength selection in fluorescence instrumentation. Erdogan T.
Source: Semrock, Inc., Rochester, NY, USA.

Abstract
"Fluorescence imaging and analysis techniques have become ubiquitous in life science research, and they are poised to play an equally vital role in in vitro diagnostics (IVD) in the future. Optical filters are crucial for nearly all fluorescence microscopes and instruments, not only to provide the obvious function of spectral control, but also to ensure the highest possible detection sensitivity and imaging resolution. Filters make it possible for the sample to "see" light within only the absorption band, and the detector to "see" light within only the emission band. Without filters, the detector would not be able to distinguish the desired fluorescence from scattered excitation light and autofluorescence from the sample, substrate, and other optics in the system. Today the vast majority of fluorescence instruments, including the widely popular fluorescence microscope, use thin-film interference filters to control the spectra of the excitation and emission light. Hence, this unit emphasizes thin-film filters. After briefly introducing different types of thin-film filters and how they are made, the unit describes in detail different optical filter configurations in fluorescence instruments, including both single-color and multicolor imaging systems. Several key properties of thin-film filters, which can significantly affect optical system performance, are then described. In the final section, tunable optical filters are also addressed in a relative comparison."
http://www.ncbi.nlm.nih.gov/pubmed/21455966

Edit: Here's one supplier: http://www.madebydelta.com/delta/Business_units/LO/Filters/Filters_main.page
 
Last edited:
Carroll1 said:
<snip>Is there any way to filter out all other light except for the light at the emission frequency from an iPhone/Android camera?<snip>

I suspect you are going to need a filter in front of the camera, but a quick way to check is to take a picture of (for example) an arc lamp and see if you can pull out the discrete lines.

These folks used external optics:
http://www.spectroscopynow.com/deta...hone-turns-into-a-spectrometer.html?tzcheck=1
If you only want to detect the signal and not image, you may be able to use this:
http://download.cnet.com/spectraSnapp/3000-20415_4-75823442.html
 

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