Cost Analysis

Contents

Overview and Motivation
Methodology
Results
Conclusions

Overview and Motivation

During our human practices discussion with the Police it was brought to our attention that not all officers carry a breathalyser device and they are rather bulky: our patch could be an alternative, compact solution that all officers could carry provided it was suitable.

This obviously introduces constraints to the device if is to be suitable for this purpose.

Constraint Summary	Constraint	Reasoning	Value
Maximum expression time	The AlcoPatch would need to equally as fast as current methods, if not faster. This would increase the likelihood of uptake as it is an improvement on the current portable methods of blood alcohol detection	Requirement suggested during the discussion	120 seconds
Minimum expression amount	Expression needs to be high enough that the result can be seen since the device it designed to be portable and used 'roadside' where lighting conditions may not be ideal	Reference (PLACEHOLDER)	17.4 mM

Wallach, Jacques. Interpretation of Diagnostic Tests. Disorders due to Physical and Chemical agents. 8thed. Lipincott Williams and Wilkins: 2007. 11.4mM from below Goldberg, R.B., 2009. Cytokine and cytokine-like inflammation markers, endothelial dysfunction, and imbalanced coagulation in development of diabetes and its complications. The Journal of Clinical Endocrinology & Metabolism, 94(9), pp.3171-3182.

This Human practice link was about alcohol and we ran a glucose experiment. However this link inspired us to think about Diabetes THe typical sweat concentration is Moyer, J., Wilson, D., Finkelshtein, I., Wong, B. and Potts, R., 2012. Correlation between sweat glucose and blood glucose in subjects with diabetes. Diabetes technology & therapeutics, 14(5), pp.398-402.. While this analysis is regarding Glucose not Alcohol it is included as a proof of concept of the system rather than to provide informative results. Since the majority of the project focused on Alcohol however these constraints were still used as all analyses should be informed and guided by the human practices.

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Methodology

The model was run for a range of different enzyme ratios, maintaining a constant total amount of enzyme

The concentration of Glucose used in the model was set to the concentration equivalent to the sweat alcohol concentration of someone who was on the legal limit of drink driving.

$$ [E_{total}] = [GOx] + [HRP]$$

All simulations that didn't violate the constraints were recorded

$$[ABTS_{Oxidised}]_{t_{max}} > [ABTS_{Oxidised}]_{min}$$

The cost of the simulation was estimated assuming the cost of everything but the enzyme costs are negligible

$$Cost_{total} = Cost_{GOx} [GOx] + Cost_{HRP} [HRP]$$

The highest total cost from all the ensemble runs was treated as the final value andTotal Cost vs Fraction of GOx was then plotted

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Results

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Conclusions

From the graphs you can clearly see that the minimum cost can be achieved with the range GOx fraction is approximate 0.6 and the total amount of enzyme is 0.01 mM. The ranges identified as of interest should be tested experimentally to further validate these results. The range that satisfies the constraints is fairly small at low amounts of total enzyme and increases with increasing total amount of enzyme. Depending on the tolerances of the patch production it may be favourable to chose a large total amount of enzyme to increase the acceptable range so that the patch remains within specification.
It can also be seen that the optimum solution is always the maximum acceptable amount of GOx.

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