Development of selective and highly sensitive organic thin film transistor based bio sensors

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Wearable or implantable, sensor-laden devices can detect key physiological parameters, store data, and even deliver drugs when needed. The use of organic electronics is either essential or highly beneficial to the functioning of all these applications. Organic electronics are devices that use conductive carbon based materials instead of silicon. They are relatively inexpensive to manufacture and can easily be integrated into flexible and even biocompatible substrates. However, as an emerging technology, more research is needed to improve performance, device stability and lifetime, and to understand, as well as predict, device interaction with biological environments. Organic thin film transistors (OTFTs) are based on field-effect controlled current allowing for basic logic-gate operations. OTFT-based sensors have been used in numerous applications, such as glucose sensing, for in-situ medical diagnostics, detecting explosive materials, building artificial skin or “e-skin” for next-generation robotics/health monitoring, and as an electronic nose for detection of spoiled food. My research group has used both n-type and p-type-based OTFTs to fabricate specific DNA sensors and Cannabinoid-based sensors. The versatility inherent in organic small molecules and polymers facilitates a unique chemical response between an analyte of interest and the active material, and can subsequently translate this response into an electrical signal. We have also studied the effect of different environments on various semiconductor materials and OTFT operation, which is key to understanding the potential use of materials in sensors. The major challenge is that these sensors do not produce enough current when exposed to analytes and therefore must be characterized using expensive electrical source meters. For hand held, point of care operation using off the shelf electronic components we require significant increases in current from the resulting sensors. This program aims to improve the absolute current generated and the current differential generated from the sensors through: A) Engineering air stable and high performing silicon phthalocyanine semiconductors; B) Development of high capacitance poly(ionic liquid) block copolymer electrolyte gating medium and C) High performing devices through directional shearing and surface induced crystallization. Finally, this program will enable the design and development of a platform to evaluate highly selective disposable point of care biosensors. From on the spot detection of food decay and food born pathogens for improved food safety to the detection of narcotics for improved law enforcement: this type of sensor platform has a plethora of viable commercial applications.