Table 2. Validation of the relationship between the measured strain in cardiac microtissue wells (i.e. distance between posts) and strain applied to the entire PDMS well.

The PDMS well was stretched using the constructed stretching bioreactor. Images were taken of the PDMS platform at each of the four strain settings of 5, 10, 15 and 20%. The actual distance between the posts was measured and percentage error between the desired stretch and the average actual stretch was calculated as follows:

$$\mathit{\text{Percent Error}}=\frac{|\mathit{\text{Measured Strain}}-\mathit{\text{Applied Strain}}|}{|\mathit{\text{Applied Strain}}|}*100$$

Average Measured Strain (%)	Applied strain (%)	Percent Error (%)
4.7 ± 0.1	5	9.8 ± 2.9
10.5 ± 0.9	10	7.7 ± 4.1
13.3 ± 0.2	15	12.5 ± 2.0
16.9 ± 0.6	20	18.4 ± 4.4