Organic Charge Modulated Field–Effect Transistor-Based Pressure Sensor Operated by Electrospun Piezoelectric Polymer

Organic Field Effect Transistor (OFET) was a basic electronic device, and due to its high structure and signal amplification effect, it was receiving high attention for the development of pressure and chemical sensors and its application potential in the field of wearable electronics. However, in the case of an OFET-based sensor, since an active layer that could detect a signal is formed on top of the source/drain or gate electrode and works, the basic component of the device was damaged by external stimuli, and finally the stability of the unit device, There were issues with performance and reliability degradation. Organic Charge Modulated FET (OCMFET) had a characteristic where the voltage applied to the control gate was induced through an insulator and a operating voltage was applied to the floating gate, and depending on the voltage applied to the control gate, it was possible to control the carrier required to operate the element. Also, by configuring the sensing area in the extended floating gate, it could be applied as a sensor and operation of the element without damaging the components of the FET, so it was advantageous in terms of securing the stability of the element. In this study, an OCMFET was fabricated using Dinaphtho[2,3-b:2′,3′-f ]thieno[3,2-b]-thiophene (DNTT) organic semiconductor and anodized AlOx dielectric, and pressure sensor was fabricated by applying electrospun PVDF-TrFE-elastomeric template with piezoelectric properties to floating gate. The PVDF-TrFE mat fabricated using electrospinning induced the alignment of b-crystals in the polymer by the applied voltage and the strong elongation force applied therewith, so it had high piezoelectric performance without the poling process. In addition, the template was fabricated by impregnating PDMS to impart elastomeric properties to PVDF-TrFE mat. The OCMFET-based pressure sensor developed through this study exhibits stable FET performance, so it can be applied to various wearable sensor fields such as human motion monitoring, biomedical, and artistic intelligence in the future.