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Senior Design

Students in the Department of Biosystems and Agricultural Engineering complete a two-semester capstone consisting of BAE 402 and 403. During the senior design process, students tackle an open-ended engineering problem and produce a working prototype to solve the problem. The capstone challenges students to master skills needed to function successfully as an engineer.

 
 
 

Team Machinery
Planting Small Seeds

Arabidopsis is a common, small flowering plant that is often used in research. The seed has a small, well-sequenced genome, a rapid life cycle, and is often used in plant-pathogen interaction research.  At the beginning of each germination cycle, researchers must separate seeds into 96-well plates, a task made difficult by the extremely small size of Arabidopsis seeds, 200 to 500 µm in diameter. Each seed must be separated by toothpick and placed into a well, such that each research cycle includes 40 hours of preparatory work during which seeds are planted in 100 plates.  A device that would speed up this process would save time and money. Several alternatives were considered and a pipette tip design was chosen based on the cost, ease of assembly and operation, and effectiveness. The final design was fabricated out of a polycarbonate plastic, formed via injection molding. It allowed operators to pick up, hold, and place Arabidopsis seeds from a container to a well plate in a short period of time. Additionally, it could correct errors by picking up any duplicates out of the well and relocating the seed to another. It will save operators a yearly sum of 204 man-hours, allowing researchers to focus on more technical tasks. The prototype was tested in six trials, in which two rows of seeds were filled. The average researcher could fill an entire well plate in 9.83 minutes, with a 90.63% success rate. Using the pipette tip design, 100 plates could theoretically be filled in roughly 16 hours, or two full work days. 

 
 
 
 
 

Team Bioprocessing
Separating Ionic Liquids

Ionic liquids (ILs) are liquid salts that melt at room temperature. Certain ILs are promising solvents for breaking down lignocellulosic biomass for biofuel production. In a typical process, the biofuel (e.g. ethanol) will be separated by evaporation from the IL, while the remaining mixture contains leftover IL, water, and other bioproducts. In order to make this process economically attractive, it would be beneficial to recycle the IL and recover the bioproducts. The project goal was to design, fabricate and teste a separation device to recover IL from a waste mixture solution using electrodialysis. Due to the IL’s ionic property, electrodialysis is a more suitable and effective method for IL separation. A multi-pass prototype was designed and the procedures for IL concentration analysis and the testing parameters were selected. The electrodialysis chamber was 3-D printed and the parts were assembled for initial testing with saline solution. To calibrate and validate our design, various flow rates (peristaltic pump speed), strength of electrical fields (voltage), and total runtime were tested. However, we failed to tune the pump flows to identical flow rates due to the hydraulic constraints of the prototype. The main problem was the varied sizes in hand cut membranes and gaskets and tubing diameter. To solve this, having one general sized master-piece mold for the silicone gaskets and revise the diameter of the electrodialysis chamber would help to equilibrate the flow of the different streams. In future, the device can be optimized for the separation of different type of ILs and bioproducts.

 
 
 
 
 

Team Bioenvironmental
Testing Bioretention Media

Currently, there is no safe and reusable method for examining the characterization of bioretention system fill media properties in the Biosystems and Agricultural Engineering Department at the University of Kentucky. This project focused on the design of a lab-scale, reusable bioretention media testing system with the goal of maximizing operator ease of use and safety while minimizing any sidewall edge effects due to low friction losses. Four alternative designs were proposed to address these requirements. The chosen design consists of four chambers, held in individual rotating frame assemblies. Each testing chamber’s rotation is controlled by a hydraulic lift. The proof of concept testing focused on sidewall edge effects on discharge in relation to testing chamber diameter. Test results coupled with economics and future research needs guided final testing chamber diameter (8 in.) selection. The final prototype, consisting of a single testing chamber along with the frame assembly fitted with an Arduino-controlled sensor and valve (for maintaining a set water level), was constructed and tested. A commercial hydraulic lift product has been installed to enable safe rotation of the device (by limiting operator load to less than 50 lbs.). The prototype was filled with soil media for testing and the bioretention media testing system was evaluated for safety and functionality. Analysis included assessment of the design goals of safety and reusability, as well as the ease by which the constant head can be maintained and the chamber emptied of media, such as moist sand. Results indicated the system achieved the stated goals when using two operators.

 
 
 
 
 

Team Food Processing
Wind Turbine for Food Drying

In many developing countries the methods for storing and drying grains and other harvested crops are inefficient and often lead to the loss of vital agricultural products.  Due to the lack of efficiency in this process, a significant portion of the food supply can become contaminated with fungi and other microorganisms that result in widespread public health concerns. The goal of this project is to design a wind turbine system that can be used to power a fan that assists the grain drying process. After carefully analyzing three different alternative solutions the design for a horizontal axis, three blade, strictly mechanical wind turbine was chosen because of its low cost and high efficiency. This design would incorporate a gear train system to power the fan used to supply airflow to grain drying units. In the full scale design this would stand 10 m tall with a rotor diameter of 5 m. A ¼ scale model of the 5 m diameter turbine was designed and assembled in the engineering design center. After testing it was determined that the concept worked to a certain extent. When the gears were not connected and the turbine was allowed to rotate freely on its own, it reached fairly high rpms at low wind speeds. However when the whole system was assembled it would not rotate unless at high wind speeds or some initial push to overcome the polar moment of inertia in the system. In the future this could be fixed by using lighter materials that can still withstand torque values in the system or a combination of smaller gears that have the same equivalent gear ratio.

 
 
 
 
 

Team Biomedical
Equestrian Bra Development

In the world of equestrian sports, female riders often experience breast pain that is not alleviated by trying different styles of bras. Breast pain in female equestrians can be caused by tight shoulder straps, rubbing and chafing from the fabric, and the underwire in the bra. Horseback riding also results in a large amount of vertical breast displacement during riding. This displacement takes an irreversible toll on the fatty tissue that makes up the breasts, which cannot regain condition through exercise after being damaged. These added risks and long-term health consequences support a higher need to invest in an equestrian-specific bra that protects against damage to the breasts. A possible design solution to address the issue of breast pain that female equestrians experience while riding was developed. The proposed solution needed to be comfortable, supportive, and affordable. The comfort aspect involved incorporating breathable and fitting fabrics, which can also conform to several body types. By assessing the needs of a female equestrian compared to a female runner, the following design changes were implemented: a 2.5 in upper compression band, vertical strap orientation, reinforced padding, and a closure. An existing sports bra was retrofitted with a compression band that went from the back closure to the front above the top of the breasts, and tested on a subject running on a treadmill at various speeds with a force-sensing fabric inserted between the bra and the breast centered around the nipple. While the results showed a higher average pressure on the testing prototype, they also demonstrated less activity of the testing prototype, indicating reduced breast movement.