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Incremental Interface Surface Potential Measured with a Nano-Gap Coplanar Device Structure and Its Applications

Wednesday, 31 May 2017: 14:40
Eglinton Winton (Hilton New Orleans Riverside)
H. T. Hsueh, P. H. Chen, F. E. Chen, M. S. Tsai, T. W. Wu, and C. T. Lin (National Taiwan University)
Because of detection characteristics in traditional capacitive-based biomolecular sensing technologies, it is important to have a uniform and defect-free interface layers. However, efforts to achieve the interface layer are tedious and labor intensive. To conquer this problem and enhance the sensing characteristics of capacitive-based biomolecular sensing device, in our report, we use co-planar electrode with nano-gap structure and placed the sensing element on the gap surface, which is different from traditional capacitive putting antigen/antibody on the electrode surface. This arrangement leads to gap-surface charge changes as molecular binding occurring. And the altered gap-surface charges modulate the electric double layer (EDL) of electrode sidewalls and result in the change of nano-gap capacitance. Utilizing surface modification with amine-terminated and aldehyde-terminated groups, we demonstrates the proposed electrode sidewall EDL contraction phenomena induced by gap-surface ion redistribution. Based on our experimental results of surface modifications, the capacitance variance of 1 µm and 100 nm gap width are 8% and 17%, respectively. In addition, we show that both gap width and detection environment play important roles in sensitivity and detection limit of the developed nano-gap device. With a demonstration of cTnT detection, a demonstrated detection dynamic range of the proposed method is from 10 pg/ml to 1 µg/ml, which is around 100 fold higher than that of traditional capacitive biosensors. The limit of detection is 10 pg/ml, which is the cut-off level in clinical examinations.