Electromagnetic tweezers redesigned simpler, better, cheaper
Electromagnetic tweezers redesigned simpler, better, cheaper lead image
Vibrations can degrade the temporal and spatial resolution of magnetic tweezers. Caused by motors that manipulate the field strength and orientation of permanent magnets, these vibrations make some force spectroscopy measurements impossible. To remedy this, researchers have investigated alternative electromagnetic designs.
Piccolo et al. demonstrate a static design employing four solenoid coils instead of motor-driven magnets. Changing the current through orthogonal pairs of coils connected in series modulates and/or rotates the magnetic field and produces forces as high as those created by permanent magnet tweezers.
“We’re not the first to devise an electromagnetic tweezer,” said co-author David Dunlap. “However, we thought we could do it in a simpler way.”
In addition to a simpler setup than some electromagnetic tweezers, the design is easily produced with manual lathes, milling machines and other tools that are generally available to university students in shops and maker spaces. The modelling developed for the tweezers was made open source and available online.
Video tracking of DNA-tethered beads is interrupted until motor-generated vibrations subside in permanent magnet tweezers. Altering the current in the electromagnetic tweezer produces no vibrations, so the researchers can continuously monitor the response of DNA to progressive or sudden changes in twist and tension. This will allow for better profiling of protein binding and understanding of DNA motor enzymes.
The researchers estimate their design costs less than $200 to build. In the future, the researchers would like to improve the design and create a compact device that could be mounted on a variety of microscopes.
Source: “Force spectroscopy with electromagnetic tweezers,” by Joseph G. Piccolo, Joshua Méndez Harper, Derrica McCalla, Wenxuan Xu, Sam Miller, Jessie Doan, Dan Kovari, David Dunlap, and Laura Finzi, Journal of Applied Physics (2021). The article can be accessed at https://doi.org/10.1063/5.0060276 .
