Shay Timothy, Saha Tamoghna, Dickey Michael D, Velev Orlin D
Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905, USA.
Biomicrofluidics. 2020 Jun 9;14(3):034112. doi: 10.1063/5.0010417. eCollection 2020 May.
We construct and investigate paper-based microfluidic devices, which model long-term fluid harvesting, transport, sensing, and analysis in new wearables for sweat analysis. Such devices can continuously wick fluid mimicking sweat and dispose of it on evaporation pads. We characterize and analyze how the action of capillarity and evaporation can cooperatively be used to transport and process sweat mimics containing dissolved salts and model analytes. The results point out that non-invasive osmotic extraction combined with paper microfluidics and evaporative disposal can enable sweat collection and monitoring for durations longer than 10 days. We model the fluid flow in the new capillary-evaporative devices and identify the parameters enabling their long-term operation. We show that the transport rates are sufficiently large to handle natural sweat rates, while we envision that such handling can be interfaced with osmotic harvesting of sweat, a concept that we demonstrated recently. Finally, we illustrate that the salt film deposited at the evaporation pad would eventually lead to cessation of the process but at the same time will preserve a record of analytes that may be used for long-term biomarker monitoring in sweat. These principles can be implemented in future platforms for wearable skin-interfacing assays or electronic biomarker monitors.
我们构建并研究了基于纸张的微流控设备，该设备模拟了用于汗液分析的新型可穿戴设备中的长期液体收集、传输、传感和分析过程。此类设备能够持续吸收类似汗液的液体，并将其排放到蒸发垫上。我们对毛细作用和蒸发作用如何协同用于传输和处理含有溶解盐及模拟分析物的汗液模拟物进行了表征和分析。结果表明，非侵入性渗透萃取与纸质微流控技术及蒸发处理相结合，能够实现长达10天以上的汗液收集和监测。我们对新型毛细管蒸发设备中的流体流动进行了建模，并确定了使其能够长期运行的参数。我们表明，传输速率足够大，足以处理自然汗液分泌速率，同时我们设想这种处理方式可以与汗液的渗透收集相结合，这是我们最近证明的一个概念。最后，我们说明沉积在蒸发垫上的盐膜最终会导致该过程停止，但同时会保留分析物记录，可用于汗液中生物标志物的长期监测。这些原理可应用于未来用于可穿戴皮肤接口检测或电子生物标志物监测的平台。
