A Novel Synthetic Path to Nanoparticles and Highly Sensitive Nanoparticle Based Sensors
Yoo, Ho Yeon (Alex)
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A novel concept of reacting two aerosols, each containing one component of a nanoparticle was tested. Each aerosol produced droplets from a solution containing one of the nanoparticle's components. The aerosols were merged and reacted to produce the final particle. This approach has been validated using ultrasonic production of aerosols to make silver chromate, to produce light by reacting Luminol with ferric chloride and to create fluorescence under UV by reacting Umbelliferone with sodium carbonate. In addition, the concept of extending the two aerosols interaction technique was explored. The advantages of charging droplets to avoid coagulation, and controlling cavitation in order to produce droplets having very narrow size distribution, is discussed. Additionally, increasing sensitivity of QCM was studied to identify not only nanoparticle quantity but also quality. The QCM sensor has been applied for 40 years in various fields of analytical science by using the piezoelectric effect that causes changes in the QCM's frequency when a mass is added to the QCM crystal. Frequency measurements are easily made with high accuracy and sensitivity, e.g. it is easy to measure a layer of oxygen on surface of the QCM. Chapter II describes a new approach to increasing the sensitivity of quartz crystal microbalance (QCM). In this chapter, poly(methyl methacrylate) (PMMA) was used as hydroscopic layer for QCM and poly(DL-Lactide) was used to increase the surface area of the PMMA polymer layer by removing it. As a result, a much higher sensitivity was obtained as for the porous PMMA layer compared to published QCM approaches. In general, the principle of nanodroplet synthesis with an ultrasonic nebulizer with high sensitivity detection using QCM has been demonstrated to be a promising tool for nanoparticle fabrication.