Rapid fabrication of microfluidic chip with three-dimensional structures using natural lotus leaf template

This article describes a simple and rapid fabrication method for microfluidic chip with three-dimensional (3D) structures by using natural lotus leaf as a template. This microfluidic chip consists of one PDMS artificial lotus leaf substrate with micro/nano hierarchical structure and one PDMS replica with microfluidic network. PDMS artificial lotus leaf substrate is directly replicated from natural lotus leaf template by soft lithography technology. In order to seal this rough PDMS artificial lotus leaf substrate against PDMS replica, a PDMS adhesive-assisted bonding method is developed to assist the sealing of our microfluidic chip. Compared to previously reported microfluidic chips with 3D structures based on MEMS/NEMS technology, the rapid fabrication of our microfluidic chip against a natural lotus leaf template is simple, low cost, easy to control, and highly faithful without the need of expensive MEMS facility and clean room condition. As an application demonstration, we fabricate a microfluidic immunosensing chip for C-reactive protein (CRP) detection by taking advantage of its high surface area. The experiment result shows that our microfluidic chip with 3D structures has more than five times higher sensitivity than those obtained from the conventional microfluidic chip with a flat channel wall due to the increase of the surface area and consequent increase of the amount of immobilized antibody. The present microfluidic chip with 3D structures also can be applied in proteins microarray, cell culture, cell adhesion, and so on.