Liquid Metal Resistive Sensing Architectures for Measuring Diaphragm Strain Responses on Obstructed Surfaces

ABSTRACT The mechanical response of diaphragm actuators for microfluidics and soft robotics is typically characterized on flat surfaces rather than the obstructed interfaces encountered in practical devices. Upon diaphragm actuation on textured or obstructed interfaces, geometric constraints redirect the strain from uniform bending to a constrained draping mode, which is not transduced by standard strain sensing. We formulate a liquid metal‐based strain sensing architecture integrated on a circular diaphragm to measure and control diaphragm deformation on even and uneven surfaces, using a rigid bead to create an obstructed diaphragm interface. Using finite element simulations, the electrical readouts from the strain sensor on the actuated diaphragm are correlated to its progression from symmetric diaphragm deformation to constrained geometry‐induced nonlinear diaphragm deformation and eventually to saturated diaphragm deformation at the bead center, with the predicted bead‐constrained deformation showing close agreement to the cross‐sectional confocal measurements across the diaphragm. The electrical readouts from the strain sensor reflecting the deformation regimes under geometric interruptions are utilized to control diaphragm‐induced confinement on an array of beads, which is validated based on its biomolecular immobilization level. This electromechanical basis for transducing diaphragm displacement on obstructed surfaces provides a roadmap to control actuation in microfluidic and soft‐robotic systems.