Roth E J, Zimmermann C J, Disharoon D, Tasci T O, Marr D W M, Neeves K B
Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado 80045, USA.
Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado 80401, USA.
Rev Sci Instrum. 2020 Sep 1;91(9):093701. doi: 10.1063/5.0010805.
Superparamagnetic colloidal particles can be reversibly assembled into wheel-like structures called microwheels (μwheels), which roll on surfaces due to friction and can be driven at user-controlled speeds and directions using rotating magnetic fields. Here, we describe the hardware and software to create and control the magnetic fields that assemble and direct μwheel motion and the optics to visualize them. Motivated by portability, adaptability, and low-cost, an extruded aluminum heat-dissipating frame incorporating open optics and audio speaker coils outfitted with high magnetic permeability cores was constructed. Open-source software was developed to define the magnitude, frequency, and orientation of the magnetic field, allowing for real-time joystick control of μwheels through two-dimensional (2D) and three-dimensional (3D) fluidic environments. With this combination of hardware and software, μwheels translate at speeds up to 50 µm/s through sample sizes up to 5 × 5 × 5 cm using 0.75 mT-2.5 mT magnetic fields with rotation frequencies of 5 Hz-40 Hz. Heat dissipation by aluminum coil clamps maintained sample temperatures within 3 °C of ambient temperature, a range conducive for biological applications. With this design, μwheels can be manipulated and imaged in 2D and 3D networks at length scales of micrometers to centimeters.
超顺磁性胶体颗粒可以可逆地组装成称为微轮（μ轮）的轮状结构，这些微轮由于摩擦力在表面滚动，并且可以使用旋转磁场以用户控制的速度和方向驱动。在这里，我们描述了用于创建和控制组装及引导μ轮运动的磁场的硬件和软件，以及用于可视化它们的光学器件。出于便携性、适应性和低成本的考虑，构建了一个带有开放式光学器件和配备高磁导率磁芯的音频扬声器线圈的挤压铝散热框架。开发了开源软件来定义磁场的大小、频率和方向，从而允许通过二维（2D）和三维（3D）流体环境对μ轮进行实时操纵杆控制。通过这种硬件和软件的组合，μ轮在0.75 mT - 2.5 mT的磁场和5 Hz - 40 Hz的旋转频率下，能够以高达50 µm/s的速度在尺寸达5×5×5 cm的样品中移动。铝线圈夹的散热使样品温度保持在环境温度的3°C范围内，这一温度范围有利于生物应用。通过这种设计，μ轮可以在微米到厘米的长度尺度上在二维和三维网络中进行操纵和成像。
