This is a DIY Fluorometer that you can make from household items and a store bought laser. The fluorometer measures emission of the sample at the excited wavelength. This wavelength is dependent upon the laser used, since we used a simple red laser we can expect the excitation to be approximately 580 nm.

Supplies

1x Mirror

1x Glass sample holder (one with flat sides would be optimal)

1x Laser source

1x Breadboard

1x Arduino

1x Photoresistor

1x OpAmp

1x Red filter lens (red marker if nothing else available)

7x Male-to-male wires

2x Male-to-female wires

1x 100 ohm resistor

1x 220 ohm resistor

1x 10,000 ohm resistor

1x Shoebox and some electrical or black tape

Styrofoam and knives/scissors to hold the laser in place

1x Measuring cup

Samples Tested:

Olive oil, Bacardi rum (40% abv), Listerine mouthwash (22% abv)

Anything that fluoresces under red light can be used

Step 1: Electrical Diagram

The breadbox should be set up as the images show. Note that the green wire is going to ground and the red wire is going to 5V while the black wire is going to A0.

Step 2: Setting Up the Fluorometer

A shoebox needs to be used to avoid ambient light from being detected. The electrical tape is used to absorb any excess light that may enter the system and from the laser. In a fluorometer the sample holder has two mirrors at a 90 degree interface. This is to redirect the laser back to the source to avoid laser light hitting the detector and to direct any emitted light from the sample to the detector. Only one mirror was available so the electrical tape was used to add a way to reduce laser light from hitting the detector. A red marker was used to color the sample holder on the side that is close to the detector in order to filter the red light from the laser. A photodetector along with an OpAmp was used specifically to increase the signal since emission from fluorescence is extremely low and a photomultiplier was not available.

Step 3: Arduino Sketch

This is the code used for the Arduino sketch in pdf format. Copy and paste the code into the Arduino program and it should be good to go.

OpAmpPDF.pdf
Download

Step 4: Sample Testing and Recording

The samples can be tested at different concentrations to determine the effect of concentration on fluorescence. Simple dilutions can be made using different measuring devices around the house such as a measuring cup. Specific concentrations do not have to be determined as this instrument is not precise enough to determine concentrations exactly. The concentrations will be graphed versus the integer value obtained from the analogRead. This will produce an equation that can be used to determine the concentration of a sample with unknown concentration. The test we conducted used alcohol as the sample that flouresces. Different colors in the sample did seem to interfere with the data so only clear alcohol samples should be used.