Optimal molding parameter design of PLA micro lancet needles using Taguchi method

Microneedles can be used for biomedical applications such as skin prick, blood collection, and drug delivery, etc. Many of the microneedles were fabricated by traditional machining. In this study, a micro lancet needle for blood test application was fabricated using micro injection molding technique, biodegradable polylactic acid (PLA) was used as molding material. The dimension of the microneedle is 623 mum in length, 203 mum in width, and 106 mum in thickness. The mold insert for molding this microneedle was fabricated using LIGA-like techniques. ANSYS CAE software was employed to determine the microneedle´s dimensions, and the strength of microneedle was designed to withstand a pressure higher than 3.5 MPa which is necessary for breaking through human skin. Micromolding of the design microneedle was carried out using battenfeld microsystem 50 microinjection molding machine. In order to achieve optimal microneedle quality, Taguchi method was utilized in the experiment. The injection molding parameters including melt temperature, mold temperature, injection speed, and holding speed have been selected as control parameters in the experiment. Experimental results showed that melt temperature and mold temperature have the most significant effects on the strength of the PLA microneedles, and this study also demonstrates that LIGA-like and micromolding techniques can been applied for mass replication of microneedles.