Molecular diagnostics typically required expensive hardware

As the light output from Lumora's BART technology is much higher then that of other bioluminescent assays the detection instrument does not need to be as sensitive, complex and expensive. For some time we've been working with Lumora to develop a robust, portable and low-cost instrument that would allow field use of BART for applications in food safety, environmental monitoring, defence and medical diagnostics.

Concept design

The typical luminescence reader uses a photomultiplier-tube (PMT) - highly sensitive, but also relatively expensive and somewhat vulnerable. Our concept design was based on using fixed photodiodes instead, so the first question we had to answer was: "Is a detector system based on low-cost photodiodes sensitive enough?" Tests run on a quick proof-of-concept model confirmed this to be the case.

The next step was to build a breadboard system that could run a full assay with 8 samples simultaneously. The BART technology works best at elevated temperatures of around 55°C so we included a temperature controlled block that can hold 8 standard microtubes - using an off-the-shelf PID temperature controller. We also designed and build an 8-channel detector board, with a layout optimised for low noise as the photocurrents involved are in the range of a pico-ampere. The breadboard gave out raw light output measurement data that we subsequently processed off-line on a PC - at this stage of the project the most flexible solution. Results from our breadboard tests comfirmed that our multi-channel design was practically feasible.

Product development

The commercial product was to be a stand-alone instrument that did not require connection to a PC, so our next step was to design and build an 8-channel lab model. From a number of mock-ups with different styling and different types of displays we eventually settled on a design with a QVGA colour touch screen. This lab model was used extensively to run assays in various locations, and was demonstrated to a number of parties interested in the BART technology. After some tweaking it proved to be robust and easy to use, and was used as a basis to build a number of slightly modified 16-channel product demonstrators for customer trials.

These demonstrations and trials have sparked a lot of interest, so we're now further engineering the 16-channel instrument to start series production.