Additively Manufactured Micro-Lattice Dielectrics for Multiaxial Capacitive Sensors

Soft sensors that can perceive multiaxial forces, such as normal and shear, are of interest for dexterous robotic manipulation and monitoring of human performance. There exists a critical need for wearable sensors that encompass sensing capabilities for external forces with wide-ranging directionality and magnitude. However, planar fabrication techniques that are typically used have significant design constraints that often prohibit the creation of functionally compelling and complex architectures. Moreover, they often require multiple step operations and precise alignment for production, which adversely affect repeatability. Additive manufacturing can address the above challenges by incorporating digital design and automation to broaden the range of intricate structures possible and the reproducibility of samples. Here, we employed an additive manufacturing process based on continuous liquid interface production (CLIP) to create high-resolution (30 μm), three-dimensional, elastomeric polyurethane lattices for use as dielectric layers in capacitive sensors. We showed that the capacitive responses and sensitivities are highly tunable through designs of lattice type, thickness, and material-void volume percentage. These robust devices were able to withstand 850 loading cycles without a deterioration in performance. Microcomputed tomography (microCT) and finite element simulation were employed to elucidate the influence of lattice design on the deformation mechanism and concomitant sensing behavior. The advantage of 3D printing to make volumetric devices that match the natural contours of the human form was exhibited with examples of fully printed representative athletic equipment, including a shoe sole and helmet lining. CLIP enabled simple printing of customizable devices for capacitive sensors responsive to various external loadings.

Reference: Berman, A.†, Hsiao, K.†, Bao, Z., DeSimone, J.M., et al. “Additively Manufactured Micro-Lattice Dielectrics for Multiaxial Capacitive Sensors,” Science Advances (2024).
† These authors contributed equally to this work.