A Microtissue Platform to Simultaneously Actuate and Detect Mechanical Forces via Non-Contact Magnetic Approach

Mechanical control is essential for adaptive regulation in biological systems. This work presents a magnetic, non-contact approach to simultaneous detection and actuation in a microscale tissue testbed. The platform builds upon previously developed passive mechanical platforms, where tissues self-assemble on flexible pillars. Standard detection is typically derived from microscope images and actuation is often conducted using invasive approaches. In the presented platform, actuation and detection, both derived from magnetic fields, are demonstrated with high spatial, temporal, and force resolution resulting in a detectable 0.6 µm step-size in air. The forced deflection range is +/-125 microns (+/-10% strain), and an arbitrary magnitude step-and-settle actuation is achieved in less than 1 ms. Engineered human cardiac microtissue is used to demonstrate the capabilities of the system, as cardiac tissues generate contractions and adapt to external forces. Spontaneous contractions are monitored for an hour by a built-in sensor with a signal-to-noise of 2. Cyclic actuation at 1 Hz using a 1 mT/mm magnetic field is demonstrated, where max tissue strain is 0.3%. All this is achieved in a moderate-throughput, compact device, which is easily integrated into the typical flow of biological experimentation. Simultaneous control of actuation and detection enables decisions to be made on a sample-specific basis, and in future developments, will enable arbitrary design of the mechanical environment for 3D tissue conditioning, maturation, and control.