Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, IL, USA.
Nanotechnology. 2012 Feb 10;23(5):055709. doi: 10.1088/0957-4484/23/5/055709. Epub 2012 Jan 11.
We report Lorentz force-induced actuation of a silicon microcantilever having an integrated resistive heater. Oscillating current through the cantilever interacts with the magnetic field around a NdFeB permanent magnet and induces a Lorentz force that deflects the cantilever. The same current induces cantilever heating. With AC currents as low as 0.2 mA, the cantilever can be oscillated as much as 80 nm at resonance with a DC temperature rise of less than 5 °C. By comparison, the AC temperature variation leads to a thermomechanical oscillation that is about 1000 times smaller than the Lorentz deflection at the cantilever resonance. The cantilever position in the nonuniform magnetic field affects the Lorentz force-induced deflection, with the magnetic field parallel to the cantilever having the largest effect on cantilever actuation. We demonstrate how the cantilever actuation can be used for imaging, and for measuring the local material softening temperature by sensing the contact resonance shift.
我们报告了一种硅微悬臂梁的洛伦兹力致动，该悬臂梁具有集成的电阻加热器。通过悬臂梁的振荡电流与钕铁硼永磁体周围的磁场相互作用，产生洛伦兹力，使悬臂梁发生偏转。同样的电流会引起悬臂梁加热。在交流电流低至 0.2 mA 的情况下，悬臂梁可以在共振时以 80nm 的幅度振荡，直流温度升高小于 5°C。相比之下，交流温度变化会导致热机械振荡，其幅度比悬臂梁共振时的洛伦兹偏转小约 1000 倍。非均匀磁场中的悬臂梁位置会影响洛伦兹力引起的偏转，与悬臂梁平行的磁场对悬臂梁的致动影响最大。我们展示了如何利用悬臂梁的致动进行成像，并通过感测接触共振偏移来测量局部材料软化温度。
