A major manufacturer of environmental DNA (eDNA) sampling technologies has collaborated with researchers at the Department of Energy's (DOE) Oak Ridge National Laboratory (ORNL) to develop new materials for one of its key products. These materials deliver improved performance and can be sourced entirely within the U.S., reducing supply chain risks while boosting domestic manufacturing.
Smith-Root Inc ., based in Vancouver, Washington, plans to incorporate the new materials into the filtration system of its backpack-style sampling device, which allows users to quickly and easily collect and analyze eDNA from bodies of water. The eDNA reveals which species live in a particular habitat.
Since the eDNA collectors debuted in 2015, they have become a significant part of the company's business, and the field continues to grow rapidly, said Austen Thomas, a research scientist at Smith-Root who participated on the project. Customers in conservation routinely use the devices to survey rivers, streams and lakes to determine which organisms are living there. The devices also play an increasingly prominent role in biomonitoring conducted as a part of the licensing or relicensing process for hydropower dams, which often require dam operators to inventory species in the associated river and reservoir.
Addressing a challenge for industry
For years, many customers have been asking Smith-Root to switch out single-use plastic parts in the devices' filters with biodegradable or recyclable components. The company also wanted to reduce its dependence on international suppliers by sourcing materials closer to home.
Smith-Root worked with ORNL through the Water Power Technical Collaboration Program (Water Power TCP) , an initiative funded by DOE's Hydropower and Hydrokinetic Office that aims to derisk the development of innovative water power technologies for U.S. industry. The company came with a question: Could scientists at the lab identify or develop recyclable or biodegradable materials that meet performance requirements, are readily manufacturable, and are available in the U.S.?
It was a tall order, and exactly the kind of challenge that principal investigator, Peter Wang, likes best.
"My favorite thing is systems engineering, where you look at a big, complex problem and break it down into a whole bunch of different engineering disciplines," said Wang, a mechanical engineer and research staff scientist at the DOE's Manufacturing Demonstration Facility (MDF) at ORNL. "Then you pull in the appropriate experts to solve it."
ORNL is uniquely suited to the task. The scientific staff has expertise in chemistry, materials development and testing, manufacturing, biology and ecology. Wang knew exactly who to recruit for the project. He had already worked with Smith-Root on another collaboration at ORNL: the effort to build an automated, aquatic eDNA collector called "eDNA-bot," which is still in development. For this filtration system challenge, Peter brought together a team that included the principal investigator on eDNA-bot, Molecular Ecologist Kristine Moody, and two colleagues at the MDF, Cait Clarkson, a materials engineer, and Amber Hubbard, a chemical engineer. Both engineers specialize in polymers and polymer composites, with a focus on creating bio-based materials from waste products that can be sourced domestically.
Evaluating materials for performance
The group set to work, and within a few months it had identified two viable options that can be easily acquired in the U.S. and manufactured on an industrial scale. A full report on their findings can be found here .
The project focused on one part of the eDNA collection device: the plastic and rubber housing around the filter. The first step in the process was to develop a short list of alternatives, each of which was bio-based to some degree. Some of the candidate materials came from what Hubbard called the MDF's "library of thermoplastics." Others were provided by the MDF's extensive network of industry contacts. One was a wood-polymer composite material that Hubbard and Clarkson created at the lab.
To be successful, the materials had to excel in two very different venues: during eDNA collection in the field and on the production line of a factory floor. To properly preserve the eDNA and avoid contaminating the sample, the materials had to be self-drying. The materials also needed to have a certain amount of tensile strength and had to be manufacturable via injection molding.
Initial testing was done at the MDF, where researchers assessed the performance and manufacturability of the materials. Hubbard and Clarkson subjected the materials to moisture uptake analysis, assessed their ability to withstand heat distortion and evaluated their hardness.
Then Moody tested the candidate filter housing materials in ORNL's aquatics lab. She dropped pellets of each material into beakers with water containing eDNA from an albino catfish to see if the materials would alter the eDNA results in any way. Some of the materials caused the properties of the filter membrane itself to change. In one sample, the membrane became too tough to cut in half. In another, the pellets became denatured and melted onto the membrane, ruining the sample. These materials were quickly struck from the list of contenders.
For materials that passed the first round of evaluations at the aquatics lab, Moody then tested whether their presence would impact the sampler's ability to accurately detect the eDNA signal from fish, without allowing the growth of extraneous microbes that could degrade the sample.
"We found a subset of candidates that worked really well," Moody said. "They interacted with the water well, they retained the eDNA well, and they gave us a better fish signal versus microbial signal."
Advancing domestic manufacturing
The two materials that made the final cut are cheaper than the current material, met or exceeded performance requirements and are readily available in the U.S. One was the wood-polymer composite created by ORNL, which could be used for the top part of the filter housing. It performed well and is equally manufacturable when compared to the material it may replace. A second material for the bottom housing improved the filter's self-drying function by 81 percent and is 100 percent bio-based and compostable. Both materials can be sourced domestically.
"It was a pleasure as a scientist to work with the staff at ORNL," Thomas said. "Being able to bounce ideas off of them was a real benefit to us."
Smith-Root and ORNL plan to advance the project by testing the materials' manufacturability through scaled injection molding trials of demonstration parts. Smith-Root will also do further testing on the materials' performance in the water with fish, assessing it at a hatchery where they can compare how the materials function in water at a variety of temperatures and salinities.
This project was conducted as part of the Water Power Technical Collaboration Program and leveraged the capabilities of the DOE Manufacturing Demonstration Facility at ORNL.
UT-Battelle manages ORNL for the DOE's Office of Science. The Office of Science is the largest supporter of basic research in the physical sciences in the United States and is committed to addressing some of the most pressing challenges of our time. For more information, visit energy.gov/science . - Clare Kennedy
