On-demand delivery of substances has been demonstrated for various applications in the fields of chemistry and biomedical engineering. Single-pulse release profile has been shown previously for micro/nanoparticles in different form factors. However, to obtain a sustained release, a pulsatile release profile is needed. Here, we demonstrate such a release profile from polymer magnetic nanocomposite microspheres loaded with chemicals. By exciting the microactuators with AC magnetic fields, we could achieve up to 61% cumulative release over a five-day period. One of the main advantages of using a magnetic stimulus is that the properties of the environment (e.g., transparency, density, and depth) in which the particles are located do not affect the performance. The operating magnitude of the magnetic field used in this work is safe and does not interact with any nonmetallic materials. The proposed approach can potentially be used in microchemistry, drug delivery, lab-on-chip, and microrobots for drug delivery.

中文翻译：

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聚合物纳米复合材料微致动器，用于通过高频磁场激发按需释放化学物质。

在化学和生物医学工程领域的各种应用中，已证明了按需交付物质。先前已经显示了不同形状因数的微米/纳米颗粒的单脉冲释放曲线。但是，为了获得持续释放，需要脉动释放曲线。在这里，我们证明了这种从载有化学物质的聚合物磁性纳米复合微球中释放出来的特性。通过用交流磁场激励微致动器，我们可以在五天内实现高达61％的累积释放。使用磁刺激的主要优点之一是颗粒所处的环境特性（例如，透明度，密度和深度）不会影响性能。在这项工作中使用的磁场的工作强度是安全的，不会与任何非金属材料发生相互作用。所提出的方法可以潜在地用于微化学，药物递送，芯片实验室和用于药物递送的微型机器人。