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.

中文翻译：

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毛细蒸发传输的纸质可穿戴设备中的长期流体处理原理。

我们构建和研究基于纸张的微流体设备，该设备可对新型可穿戴设备中的长期流体收集，运输，传感和分析进行建模，以进行汗液分析。这样的设备可以连续芯吸模仿汗液的液体并将其丢弃在蒸发垫上。我们表征和分析毛细作用和蒸发的作用如何可以协同地用于运输和处理包含溶解盐和模型分析物的汗液模拟物。结果指出，无创渗透提取结合纸微流体和蒸发处理可以使汗液收集和监测时间超过10天。我们对新型毛细管蒸发设备中的流体流动进行建模，并确定可使其长期运行的参数。我们显示出传输速率足够大，可以处理自然出汗率，同时我们设想这种处理可以与渗透性汗液的收获相关，这是我们最近展示的一个概念。最后，我们说明了沉积在蒸发垫上的盐膜最终将导致该过程的停止，但同时将保留可用于汗液中长期生物标志物监测的分析物记录。这些原则可以在可穿戴式皮肤接口检测或电子生物标记物监测仪的未来平台中实现。我们说明了沉积在蒸发垫上的盐膜最终将导致该过程的停止，但同时将保留可用于汗液中长期生物标志物监测的分析物记录。这些原则可以在可穿戴式皮肤接口检测或电子生物标记物监测仪的未来平台中实现。我们说明了沉积在蒸发垫上的盐膜最终将导致该过程的停止，但同时将保留可用于汗液中长期生物标志物监测的分析物记录。这些原则可以在可穿戴式皮肤接口检测或电子生物标记物监测仪的未来平台中实现。