Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States.
Department of Radiology, Stanford University, Stanford, California 94305, United States.
ACS Nano. 2020 Dec 22;14(12):16194-16201. doi: 10.1021/acsnano.0c08622. Epub 2020 Nov 23.
Electronic biosensors are a natural fit for field-deployable diagnostic devices because they can be miniaturized, mass produced, and integrated with circuitry. Unfortunately, progress in the development of such platforms has been hindered by the fact that mobile ions present in biological samples screen charges from the target molecule, greatly reducing sensor sensitivity. Under physiological conditions, the thickness of the resulting electric double layer is less than 1 nm, and it has generally been assumed that electronic detection beyond this distance is virtually impossible. However, a few recently described sensor design strategies seem to defy this conventional wisdom, exploiting the physics of electrical double layers in ways that traditional models do not capture. In the first strategy, charge screening is decreased by constraining the space in which double layers can form. The second strategy uses external stimuli to prevent double layers from reaching equilibrium, thereby effectively reducing charge screening. In this Perspective, we describe these relatively new concepts and offer theoretical insights into mechanisms that may enable electronic biosensing beyond the Debye length. If these concepts can be further developed and translated into practical electronic biosensors, we foresee exciting opportunities for the next generation of diagnostic technologies.
电子生物传感器非常适合现场部署的诊断设备，因为它们可以小型化、批量生产，并与电路集成。不幸的是，由于生物样本中存在的移动离子会屏蔽目标分子的电荷，这极大地降低了传感器的灵敏度，因此此类平台的开发进展受到了阻碍。在生理条件下，由此产生的双电层的厚度小于 1nm，并且通常认为，超出此距离的电子检测实际上是不可能的。然而，最近描述的一些传感器设计策略似乎违背了这一传统观点，以传统模型无法捕捉的方式利用双电层的物理特性。在第一种策略中，通过限制双电层形成的空间来减少电荷屏蔽。第二种策略利用外部刺激阻止双电层达到平衡，从而有效地减少电荷屏蔽。在本观点中，我们描述了这些相对较新的概念，并提供了可能使电子生物传感超越德拜长度的机制的理论见解。如果这些概念能够进一步发展并转化为实用的电子生物传感器，我们可以预见到下一代诊断技术的令人兴奋的机会。
