In medical treatment, the detection of pathogens at an early stage of diseases is a key step to set up an appropriate diagnosis. To reach this goal, several techniques have been elaborated for point-of-care diagnostic applications. One of the state-of-the art methods is the application of biosensor devices. Label-free versions of them ensure an appropriate detection of pathogens from fluid samples by their relative sensitivity, rapidity and portability, thus offering a feasible and affordable alternative to the traditional diagnostic techniques. The aim of the present study is to fulfill these requirements with a cheap construction of an electro-optical biosensor, for application as a rapid test in clinical diagnostics. Hence, an integrated microsystem consisting of dielectrophoretic surface-electrodes, a rib waveguide and a microfluidic channel was created for label-free optical detection of bacteria from fluid samples. To model the efficiency of the sensor, we carried out quantitative measurements by observing the light scattered by living Escherichia coli cells located in the vicinity of the waveguide. A significant change in the scattered light pattern was observed even when objectives of moderate magnification (x10, x4.7) were used, implying that such type of sensing of the cells can be achieved by low-cost cameras, as well. The optimal frequency utilized in the process of dielectrophoretic cell-collecting was also established. With this novel system, a detection limit of ca. 10²CFU × mL⁻¹ was achieved, which is relevant to characteristic pathogen concentrations in body fluids, e.g., urine. Our further plan is to utilize this cell-gathering method in other, highly sensitive integrated optical sensor constructions, as well. The working principle of this dielectrophoretically enhanced detection of Escherichia coli cells from their suspensions gives us a low-cost and rapid-sensing alternative to routinely used, but time- and money-consuming other methods. Hence, we expect it to be readily applicable in point-of-care diagnostics as a basis of rapid tests to identify general pathogens from various body fluids.

在医学治疗中，在疾病早期发现病原体是建立适当诊断的关键步骤。为了达到这个目标，已经针对现场诊断应用阐述了几种技术。最先进的方法之一是生物传感器设备的应用。它们的无标签版本通过其相对灵敏度，快速性和便携性确保从流体样品中正确检测病原体，从而为传统诊断技术提供了一种可行且负担得起的替代方法。本研究的目的是通过廉价的光电生物传感器结构来满足这些要求，以用作临床诊断中的快速测试。因此，一个由介电泳表面电极，创建了肋形波导和微流体通道，用于对流体样品中的细菌进行无标记的光学检测。为了模拟传感器的效率，我们通过观察生物散射的光进行了定量测量大肠杆菌细胞位于波导附近。即使使用中等放大倍率（x10，x4.7）的物镜，也可以观察到散射光模式的显着变化，这意味着这种类型的细胞传感也可以通过低成本相机实现。还确定了介电泳细胞收集过程中使用的最佳频率。使用这种新颖的系统，检测限约为 10 ² CFU  ×  mL ^-1这与体液（例如尿液）中特征性病原体浓度有关。我们的进一步计划是在其他高度敏感的集成光学传感器结构中也使用这种单元聚集方法。通过双电泳增强从悬浮液中检测大肠杆菌细胞的工作原理，为我们提供了一种低成本，快速传感的替代方法，可替代常规方法，但耗时又费钱。因此，我们希望它可以作为即时测试的基础，快速应用于现场诊断，以从各种体液中识别出一般的病原体。