Surface micromachined metallic microneedles

TLDR

The paper presents a method for fabricating surface‑micromachined, hollow metallic microneedles. The process employs electroplating of palladium, palladium‑cobalt alloys, and nickel to create single needles and arrays with complex tip geometries, micro barbs, penetration stops, and multiple fluid ports, achieving lengths of 200 µm–2 cm, widths of 70–200 µm, heights of 75–120 µm, and wall thicknesses of 30–35 µm. In water, the microneedles required 30 kPa to achieve 1000 µL/h and 106 kPa for 4000 µL/h flow rates.

Abstract

A method for fabricating surface micromachined, hollow, metallic microneedles is described. Single microneedle and multiple microneedle arrays with process enabled features such as complex tip geometries, micro barbs, mechanical penetration stops and multiple fluid output ports were fabricated, packaged and characterized. The microneedles were fabricated using electroplated metals including palladium, palladium-cobalt alloys and nickel as structural materials. The microneedles were 200 mm-2.0 cm in length with a cross-section of 70-200 μm in width and 75-120 μm in height, with a wall thickness of 30-35 μm. The microneedle arrays were typically 9.0 mm in width and 3.0 mm in height with between 3 and 17 needles per array. Using water as the fluid medium, the average inlet pressure was found to be 30.0 KPa for a flow rate of 1000 μL/h and 106 KPa for a flow rate 4000 μL/h.