Electrical impedance spectroscopy (EIS) sensors, though rapid and cost-effective, often suffer from poor sensitivity. EIS sensors modified with carbon-based transducers show a higher conductance, thereby increasing the sensitivity of the sensor toward biomolecules such as DNA. However, the EIS spectra are compromised by the parasitic capacitance of the electric double layer (EDL). Here, a new shear-enhanced, flow-through nonporous, nonplanar interdigitated microelectrode sensor has been fabricated that shifts the EDL capacitor to high frequencies. Enhanced convective transport in this sensor disrupts the diffusion dynamics of the EDL, shifting its EIS spectra to high frequency. Concomitantly, the DNA detection signal shifts to high frequency, making the sensor very sensitive and rapid with a high signal to noise ratio. The device consists of a microfluidic channel sandwiched between two sets of top and bottom interdigitated microelectrodes. One of the sets of microelectrodes is packed with carbon-based transducer material such as carboxylated single-walled carbon nanotube (SWCNT). Multiple parametric studies of three different electrode configurations of the sensor along with different carbon-based transducer materials are undertaken to understand the fundamental physics and electrochemistry. Sensors packed with SWCNT show femtomolar detection sensitivity from all the different electrode configurations for a short target-DNA. A 20-fold jump in the signal is noticed from the unique working electrode configuration in contrast to the other electrode configurations. This demonstrates the potential of the sensor to have a significant increase in detection sensitivity for DNA and other biomolecules.

中文翻译：

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电极配置对非平面，流通式多孔叉指电极中核酸检测灵敏度的影响。

电阻抗光谱（EIS）传感器尽管快速且具有成本效益，但通常会遇到灵敏度低的问题。用碳基换能器修改的EIS传感器显示出更高的电导率，从而提高了传感器对诸如DNA之类的生物分子的敏感性。但是，EIS光谱会受到双电层（EDL）的寄生电容的影响。在这里，已经制造了一种新的剪切增强型，流通式无孔，非平面叉指式微电极传感器，该传感器将EDL电容器移至高频。该传感器中增强的对流传输破坏了EDL的扩散动力学，将其EIS频谱转移到了高频。随之而来的是，DNA检测信号转移到高频，从而使传感器非常灵敏，快速，信噪比也很高。该设备包含一个微流体通道，该通道夹在两组顶部和底部相互交叉的微电极之间。一组微电极中装有碳基换能器材料，例如羧化单壁碳纳米管（SWCNT）。对传感器的三种不同电极配置以及不同的碳基换能器材料进行了多参数研究，以了解基本的物理学和电化学。装有SWCNT的传感器在短目标DNA的所有不同电极配置下均显示飞秒级的检测灵敏度。与其他电极配置相比，独特的工作电极配置可注意到信号跃升了20倍。