STTR Phase I: Development of a Novel Mass/Heat Flow Sensor for an Accurate Nanobalance

这项小型企业技术转移（STTR）第一阶段研究项目将包括设计、制造和测试一种新型质量和热流传感器的原型，该传感器将允许在纳克和亚纳克水平上精确测量固体、液体和吸收气体。一种多功能和精确的质量传感器的开发将使商业仪器的后续开发能够定量测定固体、液体、残留物和吸收/吸附气体的质量，其质量小于1纳克（纳米平衡），并监测与气体反应过程中的质量变化和其他特性，或作为温度、湿度和其他环境因素的函数（纳米平衡/微热量计）。目前商用分析天平的灵敏度限制在大于一微克。该项目的目标是通过改变电极的大小和形状，并通过对电极表面进行物理和/或化学修饰，将液体（如一滴含有感兴趣分析物的溶液）限制在恒定质量灵敏度的区域，从而开发出一种传感器。由此产生的传感器将能够在广泛的材料上进行纳米级测量。重新设计的石英晶体谐振器将使分析天平的灵敏度提高至少两个数量级，特别是对于微型天平，这是天平市场中增长最快的部分。它还将极大地扩展以纳克为单位同时进行重量/量热分析的材料类型和应用。一项具有巨大商业价值的应用是“液滴重力仪”的发明，这是一项测量一滴溶液中溶解固体总量浓度的新技术。液滴重力仪将在确定质量的溶剂蒸发至干燥后，以百万分之一的精度测量溶液的非挥发性残留物。对于其他难溶但有价值的材料，如合成蛋白质或DNA片段，目前的限制使其无法常规使用重力法，而需要其他不太直接和更复杂的方法来确定其溶解度。

This Small Business Technology Transfer (STTR) Phase I research project will encompass the design, fabrication and testing of prototypes for a new mass and heat flow transducer that would permit accurate measurements of solids, liquids and absorbed gases at nanogram and sub-nanogram levels. The development of a versatile and accurate mass sensor will enable the subsequent development of commercial instruments with the capabilities to quantitatively determine masses of solids, liquids, residues and absorbed/ adsorbed gases to less than one nanogram (nanobalance) and monitor mass changes and other properties during reactions with gases or as a function of temperature, humidity and other environmental factors (nanobalance /microcalorimeter). The sensitivity of commercial analytical balances is presently limited to greater than one micro-gram. The goal of this project is to develop a sensor by modifying the size and shape of the electrodes and by confining liquids, such as a drop of solution containing an analyte of interest, to a region of constant mass sensitivity by physical and/or chemical modifications of the electrode surface. The resulting sensor would enable nanogram measurements on a broad range of materials.The redesigned quartz crystal resonator will increase sensitivity for analytical balances by at least two orders of magnitude, particularly for micro-balances, the fastest growing segment of the balance market. It will also greatly expand the types of materials and applications for simultaneous gravimetric/calorimetric analysis in nanogram quantities. One application of great commercial interest is the creation of a "droplet gravimeter", a new technique which measures the concentration of total dissolved solids in a drop of solution. The droplet gravimeter will measure the nonvolatile residue of the solution with parts-per-million precision after the solvent of determined mass is evaporated to dryness. For other poorly soluble but valuable materials such as synthetic proteins or DNA fragments, current limitations preclude using gravimetry routinely, and other less direct and more complex methods are required to determine solubility.