We propose a novel cantilever device integrated with a polydimethylsiloxane (PDMS)-encapsulated crack sensor that directly measures the cardiac contractility. The crack sensor was chemically bonded to a PDMS thin layer to form a sandwiched structure which allows to be operated very stably in culture media. The reliability of the proposed crack sensor has improved dramatically compared to no encapsulation layer. After evaluating the durability of the crack sensor bonded with the PDMS layer, cardiomyocytes were cultured on the nano-patterned cantilever for real-time measurement of cardiac contractile forces. The highly sensitive crack sensor continuously measured the cardiac contractility without changing its gauge factor for up to 26 days (>5 million heartbeats). In addition, changes in contractile force induced by drugs were monitored using the crack sensor-integrated cantilever. Finally, experimental results were compared with those obtained via conventional electrophysiological methods to verify the feasibility of building a contraction-based drug-toxicity testing system.
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