Self-Propelled Magnetoelastic Biosentinels for the Detection of Pathogenic Bacteria in a Stagnant Liquid

This paper investigates the use of self-propelled magnetoelastic (ME) biosentinels to seek out and capture pathogenic bacteria in a stagnant liquid. These ME biosentinels are composed of an asymmetric-shaped ME resonator coated with a filamentous landscape phage that specifically binds with a pathogen of interest. When a time-varying magnetic pulse is applied, the ME biosentinels can be placed into mechanical resonance by magnetostriction. The resultant asymmetric vibration then generates a net force on the surroundings and hence generates autonomous motion in the liquid. As soon as the biosentinels find and bind with the target pathogen through the phage-based biomolecular recognition, a change in the biosentinel’s resonant frequency occurs, and thereby the presence of the target pathogen can be detected. In order to actuate the ME biosentinels into mechanical resonance of a desired mode, modal analysis using the three-dimensional finite element method was first performed, and the resonant frequency was determined. In addition, the net force due to the asymmetric vibration was calculated, and the resultant motion of the biosentinels was simulated. Both dynamic simulation and experimental results showed that the ME biosentinels can move autonomously through the liquid and actively bind with the target pathogen.