Development of handheld microfluidic breath-analyzer to detect tetrahydrocannabinol and other target volatile organic compounds

近几十年来，由于对大麻药用特性的了解增加，公众对娱乐性大麻合法化的支持越来越多，对大麻的看法发生了变化。通常，大麻的使用分为两类，一类是寻求减轻其疾病症状的药用使用者，另一类是希望获得欣快效果的娱乐性使用者。因此，血液中精神活性化学物质（例如四氢大麻酚（THC））的数量可能取决于使用者的类型，这是测试损害时的重要区别。目前的技术主要集中在血液和唾液样本上，由于样本采集的侵入性或准确性较差，这些都是不利的。呼气分析是一种很有前途的替代方法，因为它既没有侵入性，又因为呼气中的四氢大麻酚浓度与血液中的浓度非常接近，所以它能提供准确的结果。然而，呼气分析有许多挑战，包括控制湿度和区分呼出气体中的化学物质。我们的技术将金属氧化物半导体与特定几何形状和涂层的微流控通道配对；这提供了一种高灵敏度和选择性的检测方法，比传统方法（如气相色谱法）更加便携。我们将开发一种监测呼吸中THC的解决方案，其目标如下：(1)改善现有气体传感器技术的响应时间，(2)控制信号干扰（例如湿度），(3)开发样品收集盒，(4)使用机器学习校准设备以适应人类呼吸，(5)将传感器封装在坚固耐用的便携式装置中，以及(6)与行业合作伙伴合作验证原型并将呼吸样本与血浆中THC浓度相关联。最终，这项技术不仅将提供一种非侵入性工具，使大麻使用者能够更加了解自己的暴露程度，而且还可以包装成一种筛查工具，帮助在工作场所和执法部门执行指定的暴露限制。这意味着个人可以更好地了解他们的大麻摄入量，更安全的道路和工作环境，以及有一个新的工具来研究四氢大麻酚引起的损害的复杂性。

Perspectives on cannabis have shifted in recent decades due to increased understanding of its medicinal qualities and mounting public support for legalization of recreational use. Typically, cannabis use is separated into two categories, with medicinal users seeking to reduce symptoms of their ailment and recreational users desiring euphoric effects. Consequently, the amount of psychoactive chemicals (e.g., tetrahydrocannabinol (THC)) in the blood stream can depend on the type of user, which is an important distinction when testing for impairment. Current technology focuses on blood and saliva samples, which are unfavourable due to either invasive sample collection or poor accuracy. Breath analysis is a promising alternative as it is both non-invasive and, since the concentration of THC in breath closely matches the levels present in blood, it provides accurate results. However, breath analysis has many challenges, including controlling for humidity and discriminating between chemicals in exhaled breath. Our technology pairs a metal-oxide semiconductor with a microfluidic channel of specific geometry and coatings; this provides a highly sensitive and selective method of detection that is much more portable than conventional methods, such as gas chromatography. We will develop a solution for monitoring THC in breath in the following objectives: (1) improve response time of existing gas sensor technology, (2) control for signal interference (e.g., humidity), (3) develop cartridges for sample collection, (4) use machine learning to calibrate device to human breath, (5) package sensor within a ruggedized portable setup, and (6) validate prototype and correlate breath samples to plasma concentration of THC in collaboration with industry partners. Ultimately, this technology will not only provide a non-invasive tool that allows cannabis users to be more aware about their level of exposure but can also be packaged to serve as a screening tool to help enforce designated exposure limits in workplaces and by law enforcement. This translates into individuals having a better understanding of their cannabis intake, safer roads and work environments, as well as having a new tool to study the complexity of THC-induced impairment.