Measuring nanoparticle powder mass to prepare samples for reaction.

Author: Bree Scott | Major: Mechanical Engineering | Semester: Spring 2022

My name is BreeAnna Scott, and I am a mechanical engineering student taking additional courses in biomedical engineering with the goal to engineer devices used for medical treatments.

Over the Spring 2022 semester, I worked in Dr. David Huitink’s mechanical engineering laboratory studying the use of superparamagnetic nanoparticles, which heat up upon exposure to magnetic fields, to drive chemical reactions by providing activation energy and, in some cases, catalytic effects. It is important to investigate the most efficient methods of driving chemical reactions to save time and money in material and chemical manufacturing industries, among other applications. I aimed to determine whether nanoparticle induction heating, which uniformly heats reactants, drives reactions forward faster than traditional hot plate heating, which produces an uneven heat distribution in the reactant mixture.

I met Dr. Huitink through his Materials engineering class in Spring 2021 and joined his lab in Fall 2022, when I was trained by a PhD student, now Dr. Carlton, on nanoparticle heating. Dr. Huitink originated the idea for the current project, and I eagerly dove into reviewing background literature on the subject and devising an experimental plan that I intended to follow step-by-step through the Spring and Fall 2022 semesters. However, I soon realized that research is not a cut and dry process of precise step following, but instead is a challenging yet rewarding journey full of mountains, valleys, and unexpected turns. The research process requires and strengthens the traits of creativity, patience, and problem-solving skills.

For example, simply determining the reaction to perform for reaction rate testing was a problem-solving process with many alternatives to consider. The main methods of tracking a chemical reaction with liquid reactants include monitoring a color change, pH change, precipitate mass, evolved gas volume, or liquid mass change. Characteristics of the nanoparticles, such as their dark color in suspension, effects on pH with varying concentrations, and large size and mass compared with reactant molecules honed down on the gas collection method as the most suitable option. After investigating several gas-producing reactions, the decomposition of hydrogen peroxide was chosen as the test reaction because of its high production of oxygen gas.

To measure the amount of gas produced in the reaction, I intended to place an oxygen sensor in the reactant beaker. However, I found that oxygen sensors available on the market could not measure the range of oxygen concentration the project required. Therefore, I instead captured the oxygen gas in an inverted graduated cylinder initially full of water, connected with airtight tubing to the reactant beaker. Making the reaction system airtight required a seal around each of the tubes and probes projecting from the reaction vessel. I attempted to fasten a thin plastic material over the mouth of the reaction vessel and poke each of the tubes into the plastic individually to create a seal around each one. After several ineffective trials with the plastic ripping, I found success wrapping a lightweight foam clay around the mouth of the beaker and each of the protruding tubes. This trial-and-error process taught me that my research plans will not always succeed, but it is important to continue forming new ideas where old ones fail.

Next, I prepared nanoparticle samples for the reaction. The small sample sizes required measuring the nanoparticle powder mass to a precision in the ten-thousandths of a gram. Dropping a single extraneous speck sent the amount over the allowed mass, requiring me to pour some back and try again. It required many hours and much patience to prepare the necessary samples— and replacement samples after many tests failed— but it was rewarding each time I reached the correct amount. After achieving the correct nanoparticle masses and adding water and H2O2, the mixture bubbled up so much that it overflowed outside of the container. However, after several iterations, I adjusted the H2O2 concentration and beaker size to a level preventing overflow while still producing a measurable volume of oxygen.

Once I had developed a functional experimental setup, I facilitated the reaction at various nanoparticle concentrations and temperatures. Unfortunately, during several trials, I collected a portion of the data but missed a necessary portion due to human error or software malfunction. For example, with some trials, the temperature sensor software did not allow the file to be saved due to timing out or other error. With others, the camera monitoring oxygen production shut off because maximum storage capacity was reached. At one point, while analyzing data from trials that I thought had been successful, I realized that the initial temperatures of different samples varied widely, affecting the reaction rate, and I was left to start over from scratch, ensuring that future samples began at a similar initial temperature.

The engineering research process reminds me of a quote by Thomas Edison: “I haven’t failed. I’ve just found 10,000 ways that won’t work.” With each setback in the process, I learned methods that did not work, leading me to try new methods, some of which have succeeded, and others which I continue to modify. I still have a long path ahead before analyzing results on the project; however, I have learned loads of information and strategies to apply in the future of the project. I am very fortunate to have my mentor and his team of graduate and undergraduate students patiently offering helpful suggestions and advice every step of the way as I move forward.

This summer, thanks to recommendations from Dr. Huitink and my biomedical engineering professor Dr. Young Hye Song, I am attending a biomedical research internship at UAMS in Little Rock. When I return, I will pick up on the nanoparticle heating project in the Fall 2022 semester, building off all I have learned this past semester thanks to support from the Honors College research grant.