Magnetic tweezers with magnetic flux density feedback control

Area of Science:

• Biophysics
• Cell Biology
• Materials Science

Background:

• Extracellular matrix (ECM) rheology and keratinocyte mechanobiology are crucial for understanding tissue function.
• Conventional magnetic tweezers (MT) devices often face limitations in precision and control.
• Developing accessible, high-performance tools is essential for advancing mechanobiology research.

Purpose of the Study:

• To present a novel single-pole magnetic tweezers (MT) device for integration with advanced microscopy techniques.
• To enable precise exploration of extracellular matrix rheology and human epidermal keratinocyte mechanobiology.
• To provide a replicable and cost-effective instrument for basic biology laboratories.

Main Methods:

• The MT device utilizes real-time feedback control of magnetic flux density via a digital proportional-integral-derivative (PID) controller.
• Algorithms compensate for non-uniform remnant magnetization in the needle core.
• PID gain scheduling optimizes magnetization/demagnetization response times (<100 ms).

Main Results:

• The MT device achieves accurate and precise magnetic actuation forces by controlling magnetic flux density, compensating for temperature effects.
• Magnetization and demagnetization response times are less than 100 ms without overshoot.
• The device actuates 4.5 μm superparamagnetic beads with forces up to 25 nN with ±30% uncertainty from 2.5 to 40 μm.

Conclusions:

• The developed magnetic tweezers (MT) device offers a significant advancement for mechanobiology research.
• Its feedback-controlled, flux density-based actuation provides superior precision compared to current-controlled systems.
• The instrument's accessibility and performance make it valuable for exploring cell-matrix interactions and ECM properties.