Team:Sheffield/Demonstrate


Demonstrate

Production

Phase I: Develop a minimum specifications product

  1. 1. Carry out the first round of market research.
  2. 2. Redesign BrightBiotics, and focus on 600 nm for bacterial growth.

  3. 3. Develop and validate movement and detection separately.

Detection To prove our device has a functional detection unit, we needed to test how its arbitrary values compared against known absorbance values. For this we used a Helios UV / Vis spectrophotometer.

Figure 1 - Detection Unit of OPENLUX

To achieve this data, we aseptically transferred 1mL of E. coli culture into the 15mL of LB broth medium in a conical flask. We then added 300μL samples to each individual well in the microplate reader and measured the absorbance at 600nm (with an additional 300μL LB broth blank). These samples included 1x, 2x, 4x, 8x, 16x, 32x and 64x dilutions of this E. coli media.

Figure 2 - Measuring Absorbance of E. coli dilutions using a spectrophotometer
Figure 3 - Measuring Absorbance of E. coli dilutions using OPENLUX

Here we have both the OPENLUX detection units readings and the Helios spectrophotometer absorbance values from E. coli serial dilutions (0 - 26) of three different strains of E. coli in LB broth. Each dilution, from each strain, was repeated 3 times and the average was collected. As the concentration of bacteria decreases in the sample, the light intensity that passes through the well increases, giving the inverse results of the spectrophotometer readings.

To calibrate our device we used this series of serial dilutions and compared OPENLUX’s reading against the same sample in a spectrophotometer at 600 nm.

Figure 4 - Comparing the OPENLUX Detection Unit to a spectrophotometer

Comparing this absorbance reading against the value given by OPENLUX allows us to roughly see how accurate the device is and find the equation to convert future OPENLUX readings to absorbance. From this graph, we can see as light intensity decreases in OPENLUX, the absorbance recorded increases. This linear relationship shows the detection unit of the device is functional. We recorded an R2 value of 0.9309 for these comparisons showing the machine is relatively accurate to a Unicam Helios UV / Vis spectrophotometer. For future OPENLUX values, the following equation can then be used:

Which then can be rearranged to:

Using the above equation, we can then directly compare the absorbance from the OPENLUX detection unit to the Helios spectrophotometer.

Table 1 - Converting OPENLUX values into Absorbance

Comparing these absorbance values from OPENLUX against the spectrophotometer gives the following information.


Figure 5 - Comparing OPENLUX readings to a spectrophotometer

Table 2 - Comparing OPENLUX Absorbance to spectrophotometer Absorbance

Gaphically, the data looks like the following. As the data follows a very similar trend and the points for each corresponding value are alike, it can be concluded that the detection unit functions to its desired ability.

  1. 4. Combine and validate movement and detection.