TY - JOUR
T1 - Configuration and design of electromagnets for rapid and precise manipulation of magnetic beads in biosensing applications
AU - Stern, Moshe
AU - Cohen, Meir
AU - Danielli, Amos
N1 - Publisher Copyright:
© 2019 by the authors.
PY - 2019/11/1
Y1 - 2019/11/1
N2 - Rapid and precise manipulation of magnetic beads on the nano and micro scales is essential in many biosensing applications, such as separating target molecules from background molecules and detecting specific proteins andDNAsequences in plasma. Accurately moving magnetic beads back and forth requires at least two adjustable magnetic field gradients. Unlike permanent magnets, electromagnets are easy to design and can produce strong and adjustable magnetic field gradients without mechanical motion, making them desirable for use in robust and safe medical devices. However, using multiple magnetic field sources to manipulate magnetic beads presents several challenges, including overlapping magnetic fields, added bulk, increased cost, and reduced durability. Here, we provide a thorough analysis, including analytical calculations, numerical simulations, and experimental measurements, of using two electromagnets to manipulate magnetic beads inside a miniature glass cell. We analyze and experimentally demonstrate different aspects of the electromagnets' design, such as their mutual influence, the advantages and disadvantages of different pole tip geometries, and the correlation between the electromagnets' positions and the beads' aggregation during movement. Finally, we have devised a protocol to maximize the magnetic forces acting on magnetic beads in a two-electromagnet setup while minimizing the electromagnets' size. We used two such electromagnets in a small footprint magnetic modulation biosensing system and detected as little as 13 ng/L of recombinant Zika virus antibodies, which enables detection of Zika IgM antibodies as early as 5 days and as late as 180 days post symptoms onset, significantly extending the number of days that the antibodies are detectable.
AB - Rapid and precise manipulation of magnetic beads on the nano and micro scales is essential in many biosensing applications, such as separating target molecules from background molecules and detecting specific proteins andDNAsequences in plasma. Accurately moving magnetic beads back and forth requires at least two adjustable magnetic field gradients. Unlike permanent magnets, electromagnets are easy to design and can produce strong and adjustable magnetic field gradients without mechanical motion, making them desirable for use in robust and safe medical devices. However, using multiple magnetic field sources to manipulate magnetic beads presents several challenges, including overlapping magnetic fields, added bulk, increased cost, and reduced durability. Here, we provide a thorough analysis, including analytical calculations, numerical simulations, and experimental measurements, of using two electromagnets to manipulate magnetic beads inside a miniature glass cell. We analyze and experimentally demonstrate different aspects of the electromagnets' design, such as their mutual influence, the advantages and disadvantages of different pole tip geometries, and the correlation between the electromagnets' positions and the beads' aggregation during movement. Finally, we have devised a protocol to maximize the magnetic forces acting on magnetic beads in a two-electromagnet setup while minimizing the electromagnets' size. We used two such electromagnets in a small footprint magnetic modulation biosensing system and detected as little as 13 ng/L of recombinant Zika virus antibodies, which enables detection of Zika IgM antibodies as early as 5 days and as late as 180 days post symptoms onset, significantly extending the number of days that the antibodies are detectable.
KW - Biosensing
KW - Magnetic beads
KW - Magnetic tweezers
KW - Pole tip
KW - Zika virus
UR - http://www.scopus.com/inward/record.url?scp=85075567365&partnerID=8YFLogxK
U2 - 10.3390/mi10110784
DO - 10.3390/mi10110784
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C2 - 31731737
AN - SCOPUS:85075567365
SN - 2072-666X
VL - 10
JO - Micromachines
JF - Micromachines
IS - 11
M1 - 784
ER -