Additive manufacturing of high-performance carbon-composites: An integrated multi-axis pressure and temperature monitoring sensor

The additive manufacturing research confides in developing three-dimensional (3D) printing routes for the fabrication of devices with multifunctional materials in various interesting application areas such as self-healing, energy conversion/storage/harvesting, and sensing platforms. This paper reports the design optimization, fabrication, and characterization of a multi-axis pressure sensor with temperature compensation using fused filament fabrication (FFF) 3D printing of conductive carbon-based composites. Additive manufacturing offers a faster fabrication of complex structures with multiple properties such as electrical, mechanical, or thermal properties. The complex and costly metal printing can be neglected, as the 3D printing of a conductive polymer is a promising technology to utilize the electrical properties of the printed materials along with mechanical flexibilities. The present work focuses on the development of a multi-axis pressure sensor integrated with a temperature-sensing element. The pressure-sensing mechanism is based on piezoresistive behavior while temperature sensing relies on temperature-dependent resistance shift of the carbon composite. The pressure sensing part comprises a hollow structure to ensure mechanical deformation upon applied pressure while the temperature sensor is buried inside the housing material. Herein, the conductive three-dimensional printable polymer is synthesized by solution casting method with Polylactic acid (PLA), multi-walled carbon nanotubes (MWCNTs), and dichloromethane (DCM) solvent, which is transformed into filament for printing. The direction of pressure and magnitude of temperature can be evaluated separately by calibrating the responses of an applied force and temperature. Moreover, an integrated temperature sensor calibrates the shift in the electrical resistance of the pressure sensor due to the alteration in environmental temperature. The additive manufactured dual pressure and temperature sensor could open up broad applications such as human motion monitoring systems and force sensing.