Abstract

Since last decades, needs of new valuable material and reliable sensing technologies were among the researcher's focus for different industry’s application. Piezoelectric Polyvinylidene Fluoride (PVDF) polymer and its copolymer, Trifluoroethylene (TrFE), are one of these materials that can be a strong candidate for new transducers and sensors due to its electromechanical properties for force/pressure sensing in different industries such as biomedical device companies. Since PVDF is Biocompatible, a thin film of it can be integrated with biomedical devices using adhesive materials. However, it is not advisable for biomedical devices/tools to use those materials due to potential toxicity of gluing different objects inside human body. An example of such devices is laparoscopic tools used in Minimally Invasive Surgery (MIS), where PVDF film is deployed at the tip of an endoscopic grasper for force and softness sensing. To avoid toxicity problem, it is possible to deposit PVDF film directly on a potential device using a spin coating approach and fabricate it from scratch. However, it has its own challenges.
In this research, PVDF-TrFE polymer is deposited via spin coating method and treated with various post-deposition processes to investigate its piezoelectricity and amount of electroactive β phase. These processes include different post thermal annealing, the effect of spin coating speed, different layer of deposition and presence of additional hydrate salt. Using FTIR spectroscopy and SEM images, the amount of the β phase and porosity of each sample is determined. In addition, the optimum experimental study is established by considering every aspect of the fabrication process.
Finally, sample sensors are tested, their output voltage signals are verified, and the results are compared to the Comsol simulation software. This study clearly shows the effective way of deposition and fabrication of a tactile PVDF-TrFE based sensor and an enhancement methodology to have a higher β phase, piezoelectric constant and higher output voltage in order to have a better force/pressure sensitivity for different applications such as MIS’s end effector.