The Price of Transformation

We manufactured prototype transformation chips in order to evaluate the efficiency of the chips created with our method. As the method was developed to be as accessible as possible, especially to smaller labs, we also wanted to check how cost efficient microfluidics could be. We therefore calculated an approximate cost for the conventional transformation procedure that we used, as well as the cost for the transformation procedure using a chip. This showed that in theory, even a simple procedure such as transformation can be cheaper using microfluidics. With that in mind, imagine how much a low budget lab could save by simplifying a more comprehensive procedure with microfluidic chips manufactured using our method.

The cost of the chip itself was calculated based on the price of the required materials. Equipment such as the 3D-printer and pumps is not included as they are fundamental for the accessibility of the method, and usually available at universities. The chip is also calculated to last indefinitely, which is possible in theory for this evaluation as PDMS should last over two years and due to the chips being washable. However, in practice, the prototype chips could only be used a limited number of times due to human intervention, which should be solved before final application.

Table 1: Displays the costs and usage of the required materials to create one of our microfluidic chip, as well as the summarized cost per chip. All costs were first calculated in SEK and then converted into Dollars. The price for Mold Resin were taken from the Formlabs webpage, while the PDMS price were from Sigma-Aldrich . Plexiglas was bought from a local hardware store.
Chip costReagentReagent amount needed Price for amount ($)
7.968 $/chipMold Resin7.29 mL0.1301
 PDMS1/3 bag7.612
 Plexiglas2x5 cm20.2262

The protocol that we used to perform transformations on E. coli was the protocol from “Synthetic Biology: A lab manual”. The cost of transformation was therefore based on the price for all the materials required according to that protocol combined with observed usage of additional equipment such as pipette tips and gloves. When the price for all specific materials had been noted, the transformations were divided into three different types, Conventional Heat shock, Prototype Heat shock Chip and Optimal Heat shock Chip. The Conventional Heat shock is the cost for an average heat shock transformation according to the lab protocol. The prototype Heat shock Chip transformation cost is based on the usage of materials for the tests of our prototypes. The last type, Optimal Heat shock Chips is based on what we viewed as possible easy improvements if we kept working with the chips beyond this prototype.

Table 2: The cost of performing conventional heat shock transformation based on the material usage in protocols and in lab observations. All costs were first calculated in SEK and then converted into Dollars. Solutions that were mixed ourselves were priced based on their material cost. All these materials were bought throught the university, which means that we based our calculations on their cost estimate.
Conventional Heat shock:ReagentPrice per unitReagent amount needed Price for amount ($)
2.045 $/TransformationSOB media2.324 $/L950μL0.002208
 LB plates 1.198 $/plate1 plate1.198
 DNA0.1176 $/μL1μL0.1176
 Competent cells0.3518 $/50μL50μL0.3518
 Pipette tips0.01923 $/pc4 pc0.07692
 Gloves0.1923 $/pair1 pair0.1923
 eppendorf tube0.1063 $/pc1 pc0.1063
Table 3: The cost of performing our prototype heat shock transformation based on the material usage in our proof of concept tests.
Prototype Heat shock:ReagentPrice per unitReagent amount needed Price for amount ($)
1.659 $/TransformationSOB media2.324 $/L100μL0.0002324
 LB plates 1.198 $/plate1 plate1.198
 DNA0.1176 $/μL0.5μL0.0588
 Competent cells0.3518 $/50μL5μL0.03518
 Pipette tips0.01923 $/pc3 pc0.05769
 Gloves0.1923 $/pair1 pair0.1923
 eppendorf tube0.1063 $/pc1 pc0.1063
Table 4: The cost of performing a possible optimal heat shock transformation based on what we thought would be easy to remove in microfluidic chips beyond our prototype.
Optimal Heat shock:ReagentPrice per unitReagent amount needed Price for amount ($)
1.418 $/TransformationSOB media2.324 $/L100μL0.0002324
 LB plates 1.198 $/plate1 plate1.198
 DNA0.1176 $/μL0.5μL0.0588
 Competent cells0.3518 $/50μL5μL0.03518
 Pipette tips0.01923 $/pc1 pc0.01923
 eppendorf tube0.1063 $/pc1 pc0.1063

Based on the costs for each type, combined with the chip cost for the microfluidic based methods, our prototype method becomes more profitable at 21 or more transformations, while the Optimal method becomes more profitable after only 13 or more transformations.

Table 5: The results from the calculations to evaluate the amount saved when performing chip based transformation, compared to the conventional method. Fourth column shows the approximate costs for 500 transformation, while the fifth column shows the cost difference between 500 conventional transformation compared to each chip based method.
Heat Shock CalculationThe CostCheaper than ConventionalSummer Cost ($)Conv. to Chip Summer Diff. ($)
ConventionalCost = 2.045xTransformations 1022.5 
Prototype ChipCost = 1.659xTransformations + 7.968#Transformations>20837.5185
Optimal ChipCost = 1.418xTransformations + 7.968#Transformations>12717305.5

In order to get a better view of how much the microfluidic based transformation methods saves, we approximated how much we could have saved this summer if all of our transformations had been performed using a chip. Based on our competent cell usage we performed around 500 transformations this summer. This means that we get the summarized costs seen in the tables below, which means that we could have saved over 300 dollars this summer by using an optimal chip!

Heat shock transformation is a fairly simple lab procedure, yet microfluidics could potentially decrease its cost enough for us to finance all of the coffee consumed in our lab this summer, which is quite an impressive feat. Microfluidics has the ability to simplify other, much more extensive, lab procedures. This would in turn save even more money than the fair amount saved by our microfluidic chip, which could potentially be used for more lab work, the planting of trees or/and to finance fika*!

*Swedish ritual involving the consumption coffee and some sort of baked treat.