3-D conical microchannel fabricated by wet etching using Ti/Au sacrificial layer

We propose a method to fabricate conical microchannel in the glass microfluidic chip. The method is based on wet etching technique with different undercut ratio of the mask materials. By using this technique, we can fabricate the microchannel having the conical nozzle functions. The fabricated structure had highly reproducible shape. In addition, the process itself was relatively easy. The key point was to prepare an optimal sacrificial layer fabricated of Ti/Au alloy with a certain condition. The fabricated conical nozzle were utilized to transported cells smoothly from the bold channel to the narrow channel. This was because the conical nozzle had a preferable flow profiles to center cells on the cross section of the channel by the lifting force. This technology solves the problem of cell clogging at the entrance of narrow microchannel.