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Abstract: Organic thin film transistors (OTFT) are potentially very attractive for making portable and disposable DNA hybridization detection toolkits because of their ultra-low-cost manufacturing and potentially high sensitivity. To make a self-supported DNA sensor, we herein report an OTFT-based label-free DNA hybridization detection system integrating electrically read DNA hybridization sensors and microfluidic delivery channels. We previously reported DNA-doped OTFTs acting as electrically read DNA sensors. In this article, we first study physics of DNA sensitivity of OTFTs, clarifying the doping mechanism. The article also presents a method of verification of the immobilization and presence of DNA on the surface using TOF-SIMS analysis. As a further step, sources of variation of measured data and methods of minimization are discussed using a novel photolithography-based microfluidics fabrication method, directly enabling on-chip hybridization and self-supported DNA detection. By integrating the sensors with microfluidics, for the first time, we demonstrate necessary technologies required to realize disposable, rapid turn-around tools for field-deployable genetic diagnosis. [Copyright &y& Elsevier]

Abstract: We demonstrate a novel DNA hybridization detection method with organic thin film transistors. DNA molecules are immobilized directly on the surface of organic semiconductors, producing an unambiguous doping-induced threshold voltage shift upon hybridization. With these shifts, single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) are differentiated successfully. This method is expected to result in higher sensitivity than the main competitive technology, ISFET-based sensors because of the direct exposure of DNA molecules to sensitive layers. Factors that influence sensor sensitivity have been analyzed and optimum conditions have been determined using statistically designed experiments. Under the optimum conditions, the maximum difference between saturation current ratios caused by ssDNA and dsDNA reaches as high as 70%. In order to make DNA detection fast, we also demonstrate rapid on-chip electrically enhanced hybridization using the TFTs. These technologies together will enable the realization of disposable, rapid-turnaround tools for field-deployable genomic diagnosis. [Copyright &y& Elsevier]