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Abstract A highly sensitive and multi-functional pressure sensor capable of continuous pressure readings is greatly needed, particularly for precise gait pattern analysis. Here, we fabricate a sensitive and reliable pressure sensor by employing eutectic gallium indium (EGaIn) liquid metal as the sensing material and EcoFlex 00-30 silicone as the substrate, via a low-cost process. The device architecture features a microchannel, creating two independent sensing devices, and the mechanical properties of the substrate and sensing material contribute to high stretchability and flexibility, resulting in a sensitivity of 66.07 MPa−1 and a low measurement resolution of 0.056 kPa. The sensor detects applied pressure accurately and can distinguish pressure distribution across a wide area. We demonstrate high efficiency for monitoring human walking gait at various speeds when a single sensor is attached to the foot, and can differentiate between walking postures. This device has strong potential for clinical and rehabilitation applications in gait analysis.

Emerging additive manufacturing (or 3D printing) can be advantageous for developing magnetorheological fluid (MRF)-based vibration isolators (MRVIs) because their designs can be easily and efficiently customized and also in-situ fabrication and repairing can be possible. In this study, a simple and compact adaptive MRVI was fabricated by using a 3D printing method. A masked stereolithography (MSLA) 3D printer was used for the fabrication of the rubber bellow and plastic lid parts of the MRVI. The electromagnet was mounted onto the lid, the reservoir was filled with an MRF, and the lid was simply assembled with the reservoir using a 3D-printed large thread without traditionally machined components. Using a material testing machine, the damper forces of the 3D-printed MRVI were measured under a constant velocity loading condition for different magnetic fields. From these tests, the magnetic field-controllable performances of the MRVI such as the MR yield force, the dynamic force range, the dissipated energy, and the secant stiffness were obtained. For the evaluation of the long-term performance reliability of the MRVI due to the MRF sedimentation, its magnetic field-controllable performances were tracked for 156 days with the variable testing intervals. Finally, the feasibility of the 3D-printed MRVI was experimentally confirmed.