Densitometer and Fluorometer Interpreter

To begin, click the box labeled ‘Click here before plugging in the fluorometer’. Then, plug the Digispark into your computers USB port - it may take a few seconds for the combined fluorometer and denistometer to start sending readings.

Keyboard shortcuts:
r: record data
b: record a blank for transmittance/OD
t: transmittance mode
o: optical density mode
f: fluorescence mode

Last reading:


Average of last 5: NA

Average of last 10: NA

Download recorded data or all data (CSV)

More detailed usage instructions

Get the device sending readings before you follow these instructions.


Transmittance is the percentage of light passing through a sample. Use the 600nm (orange) LED to measure this.

Press t on the keyboard to set the interpreter to transmittance mode. Blank the densitometer by inserting a cuvette of distilled water and pressing b. This sets the zero point - i.e 100% transmittance.

You can set the number of readings that the densitometer averages for the blank sample while the device is off on the left tab - the more you do, the more accurate the zero point.

To read a target sample, first insert the cuvette into the holder, and close the lid. Press r to begin recording a data point. It will save continuous readings until you press r again to stop. These readings will be logged under reading 1. You can then put another sample in, repeat the same process, and the readings will be recorded as reading 2, and so on.

Optical density

Optical density also measures the amount of light passing through the sample. It is related to transmittance:

Optical density works in the same way as transmittance, except press o on the keyboard to switch to this mode.


Press f for fluorescence mode. Use the 480nm LED to switch the device from being a densitometer to a fluorometer. You don’t need to blank the flourometer. Just add you samples and press read in the same way as before.

Data is provided in arbitrary units: the light intensity as recorded by the sensor.

Exporting data

You can download all the data (i.e. including the data between readings) or just the recorded data (only those you pressed ‘r’ for). To do this, click the buttons underneath the live graph. This will download a .csv file, an free spreadsheet format that can be opened in many programs including LibreOffice, Google Sheets and Microsoft Excel.

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