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 cm3 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.

中文翻译：

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磁性微轮控制与组装的实验设计

超顺磁性胶体粒子可以可逆地组装成称为微轮（μwheels）的轮状结构，微轮（μwheels）由于摩擦在表面滚动，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磁场的硬件和软件，这些磁场组装和引导 μwheel 运动以及光学器件以将它们可视化。出于便携性、适应性和低成本的考虑，我们构建了一个挤压铝制散热框架，其中包含开放式光学元件和配备高磁导率磁芯的音频扬声器线圈。开发了开源软件来定义磁场的大小、频率和方向，允许通过二维 (2D) 和三维 (3D) 流体环境对 μwheels 进行实时操纵杆控制。通过这种硬件和软件的组合，μwheels 使用 0.75 mT-2.5 mT 磁场和 5 Hz-40 Hz 的旋转频率以高达 50 µm/s 的速度通过高达 5 × 5 × 5 cm3 的样本尺寸进行平移。铝线圈夹的散热使样品温度保持在环境温度的 3 °C 以内，这个范围有利于生物应用。通过这种设计，可以在 2D 和 3D 网络中以微米到厘米的长度尺度对 μwheels 进行操作和成像。铝线圈夹的散热使样品温度保持在环境温度的 3°C 以内，这个范围有利于生物应用。通过这种设计，可以在 2D 和 3D 网络中以微米到厘米的长度尺度对 μwheels 进行操作和成像。铝线圈夹的散热使样品温度保持在环境温度的 3°C 以内，这个范围有利于生物应用。通过这种设计，可以在 2D 和 3D 网络中以微米到厘米的长度尺度对 μwheels 进行操作和成像。