Highly sensitive hair springs to measure the contraction force of engineered cardiac tissues†
Highly sensitive hair springs are prepared through a simple, time- and cost-effective two-step method, involving a hair-winding process followed by heating in boiling water. Hooke's law was used to measure the spring constant and the lowest spring constant of the springs is 0.019 N m−1, close to that of the cantilevers used in atomic force microscopy (AFM) for cells. Besides, the cyclic tensile loading test demonstrated the stability of the springs. Furthermore, a platform based on the hair spring was developed to measure the contraction force generated by engineered cardiac tissues in vitro and the contraction force at different time points was recorded. This work provides a new insight into developing advanced biomaterials and a new way to measure cellular forces.