Department of Physics, Thin Films & Physics of Nanostructures, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany.
Faculty of Arts and Sciences, Chemistry & Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA.
Biosensors (Basel). 2013 Sep 17;3(3):327-40. doi: 10.3390/bios3030327.
Lab-on-a-chip immuno assays utilizing superparamagnetic beads as labels suffer from the fact that the majority of beads pass the sensing area without contacting the sensor surface. Different solutions, employing magnetic forces, ultrasonic standing waves, or hydrodynamic effects have been found over the past decades. The first category uses magnetic forces, created by on-chip conducting lines to attract beads towards the sensor surface. Modifications of the magnetic landscape allow for additional transport and separation of different bead species. The hydrodynamic approach uses changes in the channel geometry to enhance the capture volume. In acoustofluidics, ultrasonic standing waves force µm-sized particles onto a surface through radiation forces. As these approaches have their disadvantages, a new sensor concept that circumvents these problems is suggested. This concept is based on the granular giant magnetoresistance (GMR) effect that can be found in gels containing magnetic nanoparticles. The proposed design could be realized in the shape of paper-based test strips printed with gel-based GMR sensors.
基于芯片的免疫分析利用超顺磁珠作为标记物，但大多数磁珠在没有与传感器表面接触的情况下就通过了检测区域。在过去几十年中，已经发现了不同的解决方案，包括利用磁场力、超声驻波或流体动力效应。第一类方法利用芯片上的导电线路产生的磁场力将磁珠吸引到传感器表面。通过改变磁场的分布，可以实现对不同种类磁珠的额外传输和分离。流体动力学方法则利用通道几何形状的变化来增加捕获体积。在声流控技术中，超声波驻波通过辐射力将微米大小的颗粒压到表面上。由于这些方法都存在缺点，因此提出了一种新的传感器概念来规避这些问题。该概念基于颗粒巨磁电阻（GMR）效应，该效应可以在含有磁性纳米颗粒的凝胶中找到。所提出的设计可以实现为基于纸张的测试条的形状，并用基于凝胶的 GMR 传感器进行打印。
