化学
介电谱
电阻抗
电极
分析物
焦耳加热
分析化学(期刊)
生物传感器
扩散
色谱法
材料科学
电化学
生物化学
物理
物理化学
复合材料
电气工程
热力学
工程类
作者
Anil Koklu,Jason Giuliani,Carlos Montón,Ali Beşkök
标识
DOI:10.1021/acs.analchem.0c00890
摘要
Conventional immunosensors typically rely on passive diffusion dominated transport of analytes for binding reaction and hence, it is limited by low sensitivity and long detection times. We report a simple and efficient impedance sensing method that can be utilized to overcome both sensitivity and diffusion limitations of immunosensors. This method incorporates the structural advantage of nanorod-covered interdigitated electrodes and the microstirring effect of AC electrothermal flow (ACET) with impedance spectroscopy. ACET flow induced by a biased AC electric field can rapidly convect the analyte onto nanorod structured electrodes within a few seconds and enriches the number of binding molecules because of the excessive effective surface area. We performed numerical simulations to investigate the effect of ACET flow on the biosensor performance. The results indicated that AC bias to the side electrodes could induce fast convective flow, which facilitates the transport of the target molecules to the binding region located in the middle as a floating electrode. The temperature rise due to the Joule heating effect was measured using a thermoreflectance imaging method to find the optimum device operation conditions. The change of impedance caused by the receptors–target molecules binding at the sample/electrode interface was experimentally measured and quantified in real-time using the impedance spectroscopy technique. We observed that the impedance sensing method exhibited extremely fast response compared with those under no bias conditions. The measured impedance change can reach saturation in a minute. Compared to the conventional incubation method, the ACET flow enhanced method is faster in its reaction time, and the detection limit can be reduced to 1 ng/mL. In this work, we demonstrate that this sensor technology is promising and reliable for rapid, sensitive, and real-time monitoring of biomolecules in biologically relevant media such as blood, urine, and saliva.
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