Optically controlled fluid flow: enabling smart paper-based medical diagnostic devices

世界卫生组织（世卫组织）已将获得负担得起的、可靠的、用户友好的快速医疗诊断检测确定为全球的当务之急。无论是在发达国家还是发展中国家，即时医疗设备都是首选的诊断工具，对于目前与怀孕或糖尿病相关的相对简单的问题，只需几分钟就能给出答案。负担得起但用户友好的检测还必须针对其他主要疾病和病症，如艾滋病毒、肝炎、疟疾、结核病和一系列过敏。从简单的二元是/否结果（如怀孕测试）转向提供定量或半定量结果的测试是全球的当务之急，再加上对大大提高灵敏度和检测限度的额外要求，是诊断行业的圣杯。基于纸张的多重测试环境，其中流体流动可以路由，延迟，门控和混合，将执行这些规定并优化测试程序的结果。这就是我们新型光学辅助门控流体流动技术的目标，该技术将带来急需的变革性突破，极大地扩展基于流体的诊断设备的应用领域，即横向流动设备（lfd）和基于纸张的分析设备。虽然依赖于当前被动自吸过程的纸质流体装置可以解决一些基本功能，但使用响应性光聚合物实现可触发的按需流体流动，将通过包含以下特征，为其诊断能力提供巨大的显著变化：(a)在通道内用所需的生化试剂培养流体样品，以最大限度地提高灵敏度和检测极限；(b)定时开/关门控，允许分配预先确定的样品量进行半定量检测；(c)在所需的时间触发样品流，以进行受控和用户友好的测试；(d)在多个流动通道内进行动态流量控制，以实现多步反应。我们的建议是开发一个纸平台，通过使用低功率光学寻址的响应性光聚合物的非接触照明，可以控制液体流动的打开和关闭。这种能力将大大改变目前的被动横向流动装置（lfd）成为真正的芯片上实验室型多功能试验台，为医疗诊断和医疗保健行业带来即时和可量化的影响。

Access to affordable, reliable, user-friendly and rapid medical diagnostic tests has been identified by the World Health Organization (WHO) as a global imperative. In both the developed and developing world, point-of-care (POC) devices are the diagnostic tool of choice, where an answer is provided in a matter of minutes to questions that currently address the relatively straightforward conditions relating to pregnancy or diabetes. Affordable, but user-friendly testing must also be directed to other major complaints and conditions such as HIV, Hepatitis, Malaria, TB and a range of allergies. Moving beyond a simple binary yes/no result, as for a pregnancy test, to tests that provide a quantitative or semi-quantitative result is a global imperative and together with the added demands for greatly enhanced sensitivity and limit of detection are the holy-grail for the diagnostic industry. A multi-testing environment in a paper-based format, where fluid flow can be routed, delayed, gated and mixed will implement these provisions and optimize the outcome of the testing procedure. This is the aim of our novel optically-assisted gated fluid flow technology, which will usher in a much-needed transformative breakthrough that hugely expands the application-domain of fluidics-based diagnostic devices namely lateral flow devices (LFDs) and paper-based analytical devices. While paper-based fluidic devices that rely on their current passive self-wicking process can address some basic functionalities , enabling triggerable on-demand fluid flow using responsive photopolymers will provide a hugely significant step-change in their diagnostic capability through inclusion of the following features : (a) incubation of fluidic sample with a desired biochemical reagent within a channel to maximize the sensitivity and limit of detection; (b) timed on/off gating to allow dispensing of pre-determined sample volume for semi-quantitative detection; (c) triggering-on the sample flow at a desired time for controlled and user-friendly testing and (d) dynamic flow control within multiple flow channels to enable multistep reactions. Our proposal is to develop a paper platform where liquid flow can be controllably switched on and off via non-contact illumination of responsive photopolymers using low power optical addressing. Such a capability will massively transform the current passive lateral flow devices (LFDs) into true lab-on-chip type multi-functional test-beds bringing immediate and quantifiable impact within the medical diagnostic and healthcare sectors.