Purdue University, West Lafayette, Indiana, USA.
Lab Chip. 2016 Oct 18;16(21):4230-4236. doi: 10.1039/c6lc00945j.
The complexity of current paper-fluidic diagnostic devices is limited by their imperfect control of reagent incubation and delivery. Valves providing complete fluid obstruction and multiple actuation steps within a single paper-fluidic diagnostic would increase the range of diagnostic bioassays in these porous membranes. Here, we report the rapid fabrication of tunable wax-ink valves that are thermally actuated within porous membranes. Varying width bands of wax-ink were printed onto strips of nitrocellulose and cellulose membranes and characterized by their triggered obstruction and release of fluid wicking through the membranes. To demonstrate the utility of these wax-ink valves, we have transformed a traditional lateral flow immunoassay into a multi-step, semi-autonomous assay that enhances bacterial detection signal intensity 6-fold. The wax-ink valves are applicable to other paper fluidic assays by fully obstructing fluid flow for a sustained reaction time and are able to be actuated multiple times for sequential fluid delivery with minimal user involvement. These easily fabricated wax-ink valves are a versatile addition to the toolkit of fluidic control mechanisms required to develop more sensitive paper-based diagnostics.
当前纸质流体诊断设备的复杂性受到其对试剂孵育和输送的控制不完善的限制。在单个纸质流体诊断装置中提供完全的流体阻塞和多个驱动步骤的阀门将增加这些多孔膜中的诊断生物测定的范围。在这里，我们报告了在多孔膜内热驱动的可调谐蜡墨阀的快速制造。将不同宽度的蜡墨带打印到硝化纤维素和纤维素膜条上，并通过它们触发的阻塞以及通过膜芯吸的流体释放来对其进行表征。为了展示这些蜡墨阀的实用性，我们将传统的侧向流动免疫测定转化为多步半自主测定，将细菌检测信号强度提高了 6 倍。蜡墨阀通过完全阻塞流体流动来实现持续的反应时间，并且可以在最小的用户参与下多次驱动以进行顺序的流体输送，适用于其他纸质流体分析。这些易于制造的蜡墨阀是开发更灵敏的基于纸张的诊断所需的流体控制机制工具包的多功能补充。
