Nina Pacella

Nina Pacella stumbled upon the webpage for the Michigan Tech Biosensors Lab, directed by Keat Ghee Ong. She was looking for an experience outside the classroom. “I knew nothing about research, or what it might take to work in a research lab, but everyone in the lab was extremely open to answering my questions,” she recalls.

Less than one year later, Pacella has developed a sensor array with high sensitivity for detection of various pathogens, and published a scientific paper about her work in the journal Smart Materials and Structures.

The sensor, which is disposable, can be used to perform rapid microbial detection. Potential applications include sensing E. coli for food quality and safety or monitoring hospital-acquired infections, such as MRSA.

“The array uses magnetoelastic properties to sense certain parameters in a target analyte,” Pacella explains. “Its flower design, comprised of triangular ‘petal-shaped’ magnetoelastic material, allows us to track multiple sensors at once. This type of sensor system is very low-cost and extremely quick. The ability to sense multiple samples at once cuts down sensing time, too,” she adds. “The triangle shape of the magnetoelastic materials is significant because it greatly increases the sensitivity of the sensor and is more streamlined, allowing for more sensors to be arranged together in a smaller area.”

To date, most magnetoelastic sensors are rectangular and are designed to sense a uniform coating of target analyte over the entire sensor surface. Pacella, Ong, and the research team developed a new magnetoelastic sensor design with higher sensitivity, achieved by applying non-uniform coatings and altering the sensor to a triangular shape. The new design allows the magnetoelastic sensor to form a sensor array that requires only a fraction of the sample volume for multi-parameter sensing compared to the current sensor design.

Pacella was responsible for characterizing the response of the triangle sensors, as well as designing and building the actual handheld sensor device to hold the triangles. “The design started out as very large and bulky. Through many revisions, we eventually ended up with the streamlined flower device,” she says. “I really enjoyed the design portion because it required use of our 3-D printer, and I thought it was especially rewarding to compare previous designs with the sensor as it is today.”

In addition to increased sensitivity, triangular magnetoelastic sensors can also be formed into a polar array with their tips concentrated in a small region. As a result, only a small quantity of test sample is needed for all sensors. Pacella and the team fabricated and tested a detection apparatus, including a new sensor holder, a spiral coil, and custom electronics to demonstrate the feasibility of this sensitive magnetoelastic sensor array with a minimized sample size. Their new design may lead to the development of biological or chemical sensors for the detection of glucose, pH, Bacillus anthracis (anthrax) and other pathogens.

From Michigan Technological University Biomedical Engineering, Spring 2016.