3D Printing of PEDOT:PSS Based Photoresin for Manufacturing Metastructure Architected Pressure Sensors with High Sensitivity

There is a growing demand for flexible pressure sensors designed to meet the requirements of a wide range of applications, such as wearable electronics and robotics.^[1] Compared with traditional templates, pressure sensors utilizing 3D metastructure designs can offer high sensitivity, wide sensing range, design flexibility, and adjustable performance.^[2] However, manufacturing these multifunctional micro-detailed structures can be challenging, as it requires additional steps to cast the active material onto the printed structures.<br/>Here, we utilize a PEDOT:PSS based photoresin to 3D print body-centered cubic lattice-based pressure sensors.^[3] Using this photoresin in a DLP printer enables the manufacturing of conductive PEDOT:PSS polymer composites with high resolution (27 µm planar and 50 µm thickness) in a single step, eliminating the need for additional processes. As for the sensor design, body-centered cubic lattices are chosen due to their adjustable mechanical properties, which can help in fine-tuning the device's conductivity under applied stress.<br/>Sensors were characterized by applying compression onto samples while recording the corresponding displacement and electrical resistance. The resistance response was defined as ΔR/R₀= (R₀ − R)/R₀, where R and R₀ represent the resistance with and without compressive stress, respectively. The sensor with 30% relative density has a Young’s Moduli of 0.21 MPa and it can be adjusted by varying the relative density, as evidenced by sensors with 40% and 20% relative densities exhibiting Young’s Moduli of 0.61 MPa and 0.07 MPa, respectively. Moreover, the sensor with 30% relative density exhibited an instant response to pressure, showing a dramatic increase in ΔR/R₀ of 0.96 within the pressure range of 0-10 kPa. The sensitivity of the sensor was measured 0.86 kPa^-1 at 0-0.5 kPa, 0.19 kPa^-1 at 1-2 kPa, and 0.01 kPa^-1 at 2-10 kPa range, demonstrating its capability to operate effectively across different pressure ranges. This process has been visualized by connecting the sensor in a circuit where the LED illuminates upon applying pressure to the sensor. The intensity of the light increases with additional pressure, indicating a decrease in electrical resistance.<br/>In the future, we plan to print various lattice designs with different mechanical properties including anisotropic characteristics to manufacture sensors with a large range of sensitivities. Manufactured sensors will be used in proof of concept applications in pressure mapping or directional pressure sensing.<br/><br/>[1] Li, et al.<i> J. Mater. Chem. C</i>, 2018, 6, 11878-11892.<br/>[2] Zhao, et al. <i>Adv. Eng. Mater. </i>2023, 25, 2301056.<br/>[3] Lopez Larrea, et al.<i> ACS Appl. </i><i>Polym. Mater. </i>2022, 4, 6749−6759.