GOALI: Ink-jet nanoparticle alignment layers for multi-responsive liquid crystal gas and vapor sensing

为了在今天的环境中相互作用并发挥作用，人类神经系统发展了特定的感觉系统或器官，一个或几个专门用于每种感觉。我们熟悉的五种感官是视觉、味觉、听觉、嗅觉和触觉。我们的感官创造了喜悦和快乐，但也创造了痛苦和悲伤。在某些情况下，他们警告我们即将到来的危险，在另一些情况下，他们不警告我们，或者只有在已经太晚的时候才警告我们。该项目的重点是液晶-纳米颗粒传感器，用于对有毒气体和蒸气进行定性和定量检测。这些集成的传感器系统可以在没有任何电力的情况下，在有毒气体和蒸汽存在的情况下以文本或图像的形式显示明确的警告，并提供百万分之几的灵敏度。这些传感器的活性成分是基于反应性、喷墨打印的纳米颗粒取向层，用于向列相液晶。与无处不在的液晶显示器类似，由于存在特定的危险有毒气体和蒸气，可能会影响消防员、冲突地区的军事人员、急救人员和化学制造工人的生命和健康，因此会出现图像(或可读图案)。人体呼出的挥发性化合物传感器也可以用来监测疾病状态和疾病进展，如糖尿病、肝病或癌症。拟议活动的重点是推进最近的发现，即纳米颗粒，特别是它们的表面功能化，诱导和改变了与它们直接接触的向列相液晶分子的取向。通过应用这一概念，通过喷墨打印，合成了尺寸在1至10 nm之间、表面具有活性配体的金纳米颗粒，并将其图案化，以设计多种有害气体(氯、光气、氰化物、胺、二烷基硫化物)或较少有害气体和蒸气(酮)的传感器。纳米颗粒喷墨打印和向列相液晶与纳米颗粒和其他表面接触的光学和电光响应的既定概念相结合，可以创建高灵敏度和选择性的传感器，其中传感事件产生直接的视觉读数或警告，而不使用电力。与一家工业合作伙伴合作的拟议研究为感知有害环境和监测疾病进展提供了新的前景，包括定量和定性的、可穿戴的和远程的，并具有多种检测模式。结合模拟，在存在和不存在外加电场的情况下测量光的透射率和双折射为开发液晶传感器提供了无与伦比的数据集，用于同时定量和定性检测多种有毒和无毒气体和蒸气。总体而言，这些活动创造了先进传感器材料的知识，并促进了强大的先进材料科学教育。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

To interact and function in today's environment, the human nervous system has developed specific sensory systems or organs, one or in some cases several dedicated to each sense. The five familiar senses are sight, taste, hearing, smell, and touch. Our senses create joy and pleasure, but also pain and sorrow. In some cases they warn us from imminent danger, in other cases they do not or only when it is already too late. This project focuses on liquid crystal-nanoparticle sensors for the qualitative and quantitative detection of toxic gases and vapors. These integrative sensors systems can display an unmistakable warning in the form of text or an image in the presence of toxic gases and vapors without any electrical power, and provide parts-per-million level sensitivity. The active component of these sensors is based on reactive, ink-jet printed nanoparticle alignment layers for nematic liquid crystals. In analogy to omnipresent liquid crystal displays, an image (or readable pattern) emerges due to the presence of specific hazardous toxic gases and vapors that could affect the lives and health of firefighters, military personnel in conflict zones, first responders, and workers in chemical manufacturing among others. Sensors for volatile compounds exhaled by humans can also be used to monitor disease states and disease progression such as in diabetes, liver disease, or cancer.The focus of the proposed activities is to advance recent findings that nanoparticles and particularly their surface functionalization induce and alter the orientation of nematic liquid crystal molecules in direct contact with them. By applying this concept, gold nanoparticles in the size regime between 1 and 10 nm with reactive surface ligands are synthesized and patterned via ink-jet printing to devise sensors for multiple hazardous (chlorine, phosgene, cyanide, amines, dialkyl chalcogenides) or less hazardous gases and vapors (ketones). The combination of nanoparticle ink-jet printing and established concepts of optical and electro-optical responses of nematic liquid crystals in contact with nanoparticles and other surfaces enables the creation of highly sensitive and selective sensors, where the sensing event produces a direct visual readout or warning without the use of electrical power. The proposed research in collaboration with an industrial partner offers new prospects for sensing harmful environments and monitoring disease progression, both quantitative and qualitative, wearable and remote, and with multiple detection modes. In conjunction with simulations, measurements of light transmission and birefringence in the presence and absence of applied electric fields provide unparalleled datasets for the development of liquid crystal sensors for the simultaneous quantitative and qualitative detection of multiple toxic and non-toxic gases and vapors. Overall, these activities create knowledge for advanced sensor materials and foster strong advanced material science education.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.