1 3D-printed smart functional prototypes as sensors and actuators for robotic applications

Abstract

Soft robotics, inspired by nature, is a trending research area that is based on material science and the available mechanism (pneumatic, thermal, magnetic, electrostatic, etc.) to activate them. In the recent past, polylactic acid (PLA) has shown promising material characteristics, and researchers explored the 4D printing of PLA-based functional prototypes that can be used for high-strength biomedical applications for bovines. But hitherto, little has been explored about the sensing and actuation capabilities of PLA for implantable robotic applications in bovine. In this study, PLA extracted from biomedical waste has been used to prepare the functional prototypes (implants in bovine). Further, it has been primarily recycled by varying number of shredding cycles, and finally, feedstock filaments of the same have been prepared on the single screw extruder. For analyzing the sensing and actuation capabilities of the recycled material, the prototypes were fabricated on the fused deposition modeling setup using the following process parameters: raster angle, 45°; infill pattern, grid; printing speed, 40 mm/s; and infill density, 50%. Initially, the pressure-based sensor was designed in the high-frequency structure simulator simulation software and then tested on the vector network analyzer setup to observe the dielectric properties, that is, dielectric constant (ϵr) and loss tangent (tan δ) under the effect of pressure. Further, a hydrothermal actuator for robotic application has been programmed by mechanical force, and the shape recovery of the deformed prototype has been observed under the effect of hydrothermal stimuli. The change in dielectric properties (ϵr and tan δ) of the recycled material has been observed through the insertion loss (S21) versus resonant frequency (fr), which may be used for online health monitoring of patients through a Bluetooth device by observing the electromagnetic signal in the industrial, scientific, and medical (ISM) band.