TEM Holder System for Accurate Monitoring and Control of Environmental Conditions During in-situ Liquid Cell TEM Using Integrated pH and Temperature Sensors

The inability to dynamically image materials at atomic resolution in changing liquid environments is a significant impediment to the advancement of physical, chemical, biological, medical, and material sciences. Hummingbird Scientific, via its liquid cell holders, has greatly enhanced the ability of researchers to obtain transmission electron micrographs of materials at atomic resolution while in liquid environments. However, no product currently on the market allows the TEM data to be correlated with other environmental parameters directly measured in microfluidic cell. This proposal will aim to resolve environmental parameter measurement and control issues. These goals will be accomplished by developing and bringing to market a new in-situ TEM microfluidic holder that contains an integrated, microfabricated pH sensor and temperature sensor in addition to a heating element. This new tool will allow researchers to measure and control environmental parameters at the sample directly and will be a crucial enabling technique for opening up the possibilities of in-situ experiments in liquids where for electrochemical processes the local (change in) concentration of acids and bases at the sample are key reaction parameters. The phase I project successfully developed a working prototype of a microfluidic TEM specimen holder with integrated pH and temperature measuring capabilities. In phase II of this project, we will integrate the sensor into a single device, allowing simultaneous pH and temperature measurement, as well as temperature control. This will be integrated with control hardware and software to make a turn-key system. The broader impact/commercial potential of this project is the availability of a characterization technique that can image solid/liquid interfaces up to atomic resolution under quantifiable and accurately controllable environmental conditions. This will provide new insights into the process controlling assembly and, ultimately, function in biological systems and biomolecular material as well as insights into material microstructural changes during active electrochemical processes. Our understanding of either case is limited because, until recently, we lacked an experimental tool possessing both the spatial and temporal resolution needed to capture the formative events. While in situ TEM has emerged as an enabling capability in this regard, to develop a predictive understanding that can impact biomedical and materials technologies, we require an environment in which temperature is tightly controlled and pH is measured. This new window into these materials promises dramatic advances in our understanding of the underlying kinetic factors that control material behavior, leading to more targeted development of new materials.