Hollow metallic microneedles fabricated by combining bulk silicon micromachining and UV–LIGA technology

As one of the promising research aspects in BioMEMS, microneedle technology has been widely applied in drug delivery. Compared with the solid microneedles, hollow microneedles can provide continuous delivering drugs. However, the fabrication processes and costs of the hollow microneedles are often complex and high accordingly. We propose a low-cost method to fabricate the hollow metallic microneedles, which contains procedures of using a wet method to etch silicon wafer to get the tapered cavities firstly, filling the tapered cavities with the SU-8 photoresist, developing the SU-8 to pattern the shapes of microneedles, and electroplating one metal in the patterns to form hollow metallic microneedles. According to the method, microneedles with different shape tips that include the triangular pyramids or the rectangular pyramids have been fabricated. In addition, these microneedles have been analysed using a finite element method and tested on artificial skins, which demonstrate the strength of microneedles is sufficient for piercing skins.