Magnetic tweezers with magnetic flux density feedback control.

摘要: In this work, we present a single-pole magnetic tweezers (MT) device designed for integration with substrate deformation tracking microscopy and/or traction force experiments intended to explore extracellular matrix rheology and human epidermal keratinocyte mechanobiology. Assembled from commercially available off-the-shelf electronics hardware software, the MT is amenable replication in basic biology laboratory. contrast conventional solenoid current-controlled devices, operation of instrument based on real-time feedback control flux density emanating blunt end needle core using cascade scheme digital proportional–integral–derivative (PID) controller. Algorithms that compensate spatially non-uniform remnant magnetization develops during actuation are implemented into scheme. Through optimization PID gain scheduling, exhibits demagnetization response times less than 100 ms without overshoot over wide range setpoints. Compared current-based control, density-based allows more accurate precise forces by compensating temperature increases within due heat generated applied currents. Near field calibrations validate ability actuate 4.5 μm-diameter superparamagnetic beads up 25 nN maximum relative uncertainties ±30% positioned between 2.5 40 µm tip.