Achievements
When building the OD/F Device, our goal was to develop a system that
- is straightforward to use
- is at least as accurate as commercially available systems but at the same time costs significantly less
- produces stable, reproducible results
- weights little and is easy to carry around
- uses widely available parts and is easy to build
- can measured both optical density and fluorescence
Commercially available equipment uses lasers and a set of two fine filters, one between laser and sample and one between sample and sensor. To reduce the cost, our OD/F Device uses a simpler measuring principle: it is designed with one low-quality filter, between sample and sensor, and illuminates with an LED instead of a laser. Nevertheless, one main goal was to produce an inexpensive device. Given that, we therefore had to compromise some of the measurement quality, were we still able to produce stable, precise and good data?
[graphs showing the awesomeness of our OD/F Device]
The answer is: Yes! With the optimal design of our cuvette holder we achieved good-quality results albeit using the cheap filter.
Have we been re-invented the wheel? No!
In fact, you can find some DIY posts for turbidity meters such as [http://www.thingiverse.com/thing:74415 turbidity sensors]. However, a proper assessment of their linearity as well as a calculated OD-value are missing.
Regarding fluorescence, we are also not re-inventing the wheel. The 2010 iGEM Cambridge team actually built a very similar device, the E.glometer. However, there's no data available showing an actual comparison of the data from their device and some proven commercial system to, for example, assess linearity of the measurement.
We made a commercial assessment of the OD/F Device that results in a total cost of 60 $. The unit is built from acrylic glass for the casing. The compact design results in a weight which is less than 200g. The device can be easily connected to any power adapter via USB. The technical details and a construction manual of OD/F Device is published on our wiki.
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