Discrete microstructures of predefined size and shape are prepared using sol-gel phase-reversible hydrogel templates. An aqueous solution of hydrogel-forming material is covered onto a microfabricated silicon wafer master template having predefined microfeatures, such as pillars. A hydrogel template is formed, usually by lowering the temperature, and the formed hydrogel template is peeled away from the silicon master template. The wells of predefined size and shape on the hydrogel template are filled with a solution or a paste of a water-insoluble polymer, and the solvent is removed to form solid structures. The formed microstructures are released from the hydrogel template by simply melting the hydrogel template in water. The microstructures are collected by centrifugation. The microstructures fabricated by this method exhibit pre-defined size and shape that exactly correspond to the microwells of the hydrogel template. The method of preparing microstructures based on hydrogel templates is simple and can easily produce large quantities of the microstructures.
