Progress 08/01/11 to 03/31/13
Outputs
Target Audience: Algae are one of the most, if not the most, productive biomass crops and have photosynthetic efficiencies that are almost double that of the most productive terrestrial crop (Hannon, Gimpel, Tran, Rasala, & Mayfield, 2010). Algae have many uses including human, animal, and fish nutraceuticals (feed and feed supplements), human and animal pharmaceuticals, and oil feedstock for biofuels, bioplastics, and other bioproducts. Regardless of product, all algae will require carbon, which is sourced from the atmospheric carbon dioxide either directly or indirectly from fixed carbon (e.g. sugar). This requirement plus algae’s inherent productivity means that algae can address the NIFA Societal Challenge Areas of Food Security and Hunger, Climate Change, or Sustainable Bioenergy. Regardless of end product, all microalgae require harvesting which is generally recognized as one of the most energy intensive and costly steps in algae production. For example to produce oil, it is 20-40% of the total cost of producing a gallon of oil (Benemann & Oswald, 1996). The harvesting technology proposed here could potentially lower the energy intensity and cost of algae harvesting, improving the overall energy balance and carbon footprint. While microalgae have a fundamental advantage as one of the most productive biomass crops, their large scale use is not without technical hurdles. Characteristically, microalgae are aquatic, very small (1 to 10 µm diameter), very dilute (0.01 to 0.5% w/v), have a density similar to water, and generally do not naturally coagulate. Furthermore, downstream processing usually requires a semi-dry biomass, equivalent to 1 to 90% w/v (slurry to dry flake). As such, cultures must be significantly concentrated, making the harvest and concentration of algae an important challenge. The target audience of this work is the algal biofuel indsustry where inexpensive dewatering strategies are required. Changes/Problems: Phycal was unable to accomplish all of the originally proposed objectives of this project due to problems fabricating a defect free LDA chip in low cost plastic and clogging of the LDA channels with bubbles or algae cells. Much time was spent addressing the clogging mitigation issues which needed to be solved prior to moving forward with other project objectives. In the end, Phycal recognized that using the LDA fabricated from plastic will not be a fruitful strategy for dewatering algae in efforts to reduce the costs of producing algal biofuel. However, this project made significant advances in state-of-the-art low-cost micro-manufacturing. While better technologies now exist for the dewatering of microalgae, the advances may be applicable to other LDA applications, such as blood separation or stem cell concentration, and may also apply to other types of microdevices. Phycal and LSU will seek to transfer the knowledge of this project to those applications. What opportunities for training and professional development has the project provided? 1. Phycal hired an intern who recieved training in microfluidic testing and experimentation along with personal development in a start-up company atmosphere. 2. At Louisiana State University, graduate students and post doctoral students developed expertise in the area of high aspect ratio microfluidic fabrication. How have the results been disseminated to communities of interest? The results from this work have been presented as a poster presentation at the TechConnect Microtech 2012 Conference. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Phycal was unable to accomplish all of the originally proposed objectives of this project due to problems fabricating a defect free LDA chip in low cost plastic and clogging of the LDA channels with bubbles or algae cells. Much time was spent addressing the clogging mitigation issues which needed to be solved prior to moving forward with other project objectives. In the end, Phycal recognized that using the LDA fabricated from plastic will not be a fruitful strategy for dewatering algae in efforts to reduce the costs of producing algal biofuel. However, this project made significant advances in state-of-the-art low-cost micro-manufacturing.
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2012
Citation:
Poster Presentation: Fabrication and Characterization of HAR Microfluidic Device to Concentrate Microalgae. V.Singh, Q. Nguyen, J. Goettert, D. Yemane, J. Bargiel, C. Lane, and F. Stephenson. TechConnect Microtech 2012
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Progress 08/01/11 to 07/31/12
Outputs
OUTPUTS: Phycal and subawardee LSU presented a poster at the Microtech Conference & Expo 2012 June 18-21 in Santa Clara, CA. The intended audience was other professionals and researchers in the micro-fabrication industry, especially potential customers. The feedback was resoundingly positive. All attendees were very impressed with the innovative solution and technical accomplishments of the team. This type of high-aspect ratio, high-packing density, micron-sized features was not previously possible. LSU has posted technical marketing material including project results and new micro-manufacturing capability on the Research Highlights webpage of their Center of Advanced Microstructures and Devices at http://www.camd.lsu.edu/microfabrication/highlights/VS_AR2012_Phycal. pdf. PARTICIPANTS: Phycal, Inc., 51 Alpha Park, Highland Heights, OH 44143 Christopher Lane (PI); Jeffrey Bargiel (Research Engineer), Francesca Stephenson (Intern) CAMD/LSU, 6980 Jefferson Hwy, Baton Rouge, LA 70806 Jost Goettert (Subawardee PI), Varshni Singh (Research Scientist), Quoc Nguyen (Post-Doctoral Researcher) Professional development occurred at both facilities through an internship and a post doctoral fellowship. TARGET AUDIENCES: Target audiences included those in the micro-fabrication industry and those needing micro-fabrication. This project presented a poster at the Microtech Conference & Expo 2012 to reach this audience. PROJECT MODIFICATIONS: A delay of receiving molds and raw SUEX from their respective foundries caused a delay to the overall project. A no-cost extension was approved by NIFA.
Impacts
Manufacturing: LSU accomplished the super-high aspect ratio with high packing density of small features that was deemed impossible with current technology by many other microfabricators. 1) Conditions for successful hot embossing: It is critical that the mold surface be as smooth as possible and that edges around the holes are free of burrs so as to prevent posts from snagging and breaking during demolding. Also, PMMA proved too brittle but PC was successful. Even with PC and smooth molds, the equipment and process parameters could only successfully mold to a height of 70um (aspect ratio 7) or else the friction and stresses of demolding would break posts. 2) Capping of hot embossed LDAs in PC is not possible with hot-melt PMMA due to stress-failure of posts during pressing. It is also not possible with 100 um SUEX because it was found that SUEX does not bond with PC. 3) Production of capped LDAs via direct lithography of SUEX is possible to 350 um tall (aspect ratio 35). Capping of these with SUEX was also successful because there is good bonding when the LDA and cap are the same material. However, successful runs are low because 100 um SUEX will occasionally stretch during baking to the point where holes will open. Also, consistent quality of SUEX is important. Bad batches of SUEX would result in bubbles that created holes. Operation: 1) The first problem and solution was manifolding. We realized once the LDAs were produced, that inlet and outlet holes were almost too close to each other. This would make manifolding difficult, especially keeping outlet channels separate. 2) Once manifolded, it was found that the trapping of bubbles in the LDA was a major problem. Unsuccessful mitigation techniques included: vacuum degassing of liquid to be injected, slow wetting, fast wetting, high-pressure, pulsing, sonication, back-flushing, and use of surfactants. Success came from the use of water degassed with the "freeze-pump-thaw" method. Once bubbles are removed, tests could be conducted for a long time without further bubble formation. 3) SUEX is attractive to polystyrene fluorescent beads. This caused extensive clogging over time. Mitigation with use of surfactants was minimally successful but could be improved. Young Staff: This project involved extensive involvement of post-doctoral students and undergraduate interns. They were tasked and coached in producing their own experimental plans to fit with the overall research objectives, the laboratory techniques and equipment necessary to carry out the experiments, literature searches, working independently and in teams, and interpretation and presentation of results. In many cases, the intern proposed techniques and solutions unknown to senior staff. However, an extensive area of development and personal life-learning for the intern was her first-time dealing with industrial research, personalities, accountability, schedule management, and office politics. Coaching and feedback produced a positive change and made her a more productive individual that she will carry throughout the rest of her career.
Publications
- No publications reported this period
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