On 3D-Printed Acrylonitrile Butadiene Styrene-Based Sensors: Rheological, Mechanical, Morphological, Radio Frequency, and 4D Capabilities

Acrylonitrile butadiene styrene (ABS) one of the recyclable thermoplastics having insulating properties is being widely used as a 3D-printed substrate for Bluetooth sensing devices. But hitherto little has been reported on the 4D capabilities of 3D-printed recyclable ABS substrate-based sensors. This study reports the rheological (melt flow), mechanical (tensile), morphological (surface hardness, roughness (Ra), porosity, etc.), 3D printability, and radio frequency (RF) characteristics of primary recycled ABS substrate. Further, the 3D-printed ABS substrate samples were exposed to two different stimuli (chemical and thermal) for 10 cycles/stages to ascertain the effect on RF characteristics for ensuring 4D capabilities. The 3D-printed Bluetooth sensor has been designed for 2.45 GHz. The simulated results of the 3D-printed prototypes were verified experimentally using a vector network analyzer (VNA), which shows the appreciable response with a minimal frequency shift, thus ensuring the applicability of such sensors for Bluetooth applications. The percentage variation in the dielectric constant has been recorded to a maximum of 8% (in stage 9) and a minimum of 2% (in stage 6). Also, the dissipation factor of the substrate has been recorded to remain constant (~0.0045) indicating a factor of repeatability and hence the usability of such materials for 4D printing applications. Morphological analysis on scanning electron microscopy (SEM) reveals that the Ra of the 3D-printed ABS substrate was significantly improved (50-19 nm), hence ensuring better performance of the fabricated sensors.