Annual Report 2013–14

Professor Zhang ( above ) made reference to the movement of microorganisms and took into account certain variables, including the viscosity and velocity of the liquid, the shape and magnitude of the device, as well as the limitations of applying magnetic field as field strength decays rapidly with increase in distance from source. With a series of careful experiments and complex calculations, he found that rotating helical propellers is likely one of the best choices for in vivo applications. The shape of the device has been improved upon continuously. Most of the early microrobots came with a small body to carry drugs. In his recent research, Professor Zhang and his collaborators constructed photocurable polymer three-dimensional scaffolds with controllable porosity for different treatment purposes. The new design made a breakthrough in the quantity of drug delivered. Moreover, having a three- dimensional structure for cell culture, compared to two-dimensional in which the cell is cultured on a flat surface, is important for sustaining the structural and functional complexities of the cells because it is much closer to the in vivo environment. The new technology has the potential to revolutionize minimally invasive medical treatment and can lead to targeted treatment of various diseases such as cancer, cerebral infarction and retinal degeneration. The research results have been featured as the cover story in Advanced Materials released in November 2013. 張教授（上圖）參考了微生物的移動 方式和各種可變因數，包括流體的黏 性和速度、機械的形狀和體積，再考 慮磁場力度會隨着與機械距離漸遠而 急速減弱這限制，經過多方實驗及 複雜運算，得出以螺旋式前進，是機 械在活體內最佳的推進方式之一。 機械裝置的形狀設計亦經過不斷改 良，過往此類微型機械載藥量有限， 在最新發表的研究中，張教授與合作 者建構了一個三維的光聚合高分子多 孔微型支架，孔隙大小形狀可因應不 同醫療目的所需藥量而控制。除突破 了原有微型機械載藥量不足的限制， 三維結構相較平面的二維結構，更接 近活體環境，在微型支架上培殖細 胞，可保存細胞結構和功能上的複 雜性。 新的微型機械甚有潛力革新微創醫 療，有望應用於治療癌症、腦梗中風 和視網膜退化。 研究結果刊登於國際知名學術期刊 《先進材料》2013年11月的封面故 事。 20 開拓人類知識的版圖 Pushing Knowledge Frontiers