3D printed flexible wearable sensors based on triply periodic minimal surface structures for biomonitoring applications

Abstract

Soft piezoresistive wearable conductors have led to a paradigm shift in the monitoring of human bodily motions. Cellular additively manufactured conductors are promising piezoresistive components as they offer mechanical tunability and provide controllable percolation pathways. In the present study, we engineer high surface-area cellular structures with the triply periodic minimal surface (TPMS)-based architectures to tailor their piezoresistive response for use in wearable devices. A simple and economical fabrication process is proposed, wherein a fused deposition modeling (FDM) 3D printing technique is utilized to fabricate flexible thermoplastic polyurethane (TPU) cellular structures. Interconnectivity of TPMS designs enables the coating of a continuous graphene layer over the TPU internal surfaces via a facile dip-coating process. The effects of pore shape on piezoresistivity are studied in four different TPMS structures (i.e., Primitive, Diamond, Gyroid, and I-WP). Mechanical properties of sensors are evaluated through experimental procedures and computation methods using finite element analysis of the Mooney-Rivlin hyperelastic model. The piezoresistive performance of sensors exhibits durability under cyclic compression loading. Finally, we conclude that the Primitive structure offers suitable piezoresistive characteristics for sensing of walking, whereas the Diamond structure presents favorable results for respiration monitoring.

Ultra-Broad Linear Range and Sensitive Flexible Piezoresistive Sensor Using Reversed Lattice Structure for Wearable Electronics

“…In addition, a comparison of the sensing performance in terms of linearity, sensitivity, and linear range between the RLS sensor and other previously reported highly linear pressure sensors was conducted, as shown in Figure S23 and Table S1. Our sensor has achieved outstanding performance in ultra-broad linear pressure sensing, which, to the best of our knowledge, has not been previously reported and has been challenged. ,,,,,− Furthermore, a comparison with other 3D printed flexible porous sensors was conducted and listed in Table S2, demonstrating its distinguishable characters with broad linear range, compact size, and without 3D model design. − ,− …”

Piezoresistive Porous Composites with Triply Periodic Minimal Surface Structures Prepared by Self-Resistance Electric Heating and 3D Printing

“…In addition, the sensors with TPMS structure exhibit higher resilience than those with bulk structure. Imanian et al [14] engineered soft piezoresistive wearable conductors with TPMS-based architectures and evaluated the effects of pore shape on piezoresistivity in four different TPMS structures (i.e., Primitive, Diamond, Gyroid, and I-WP). Davoodi et al [15] fabricated durable and flexible 3D conductive sensors with interconnected TPMS structures, and found that different structural cell types could result in different gauge factors.…”

3D printing polyurethane acrylate(PUA) based elastomer and its mechanical behavior

“…TPMS are mathematical structures that are known for their unique geometry and mechanical properties [15][16][17]. In recent years, 3D printing technology has been utilized to fabricate TPMS lattice structures using elastomeric materials such as TPU, silicone, and rubber [18,19]. One advantage of using 3D printing to fabricate TPMS lattice structures is its ability to create complex and highly customizable geometries.…”