Microneedle array with integrated microchannels for transdermal sample extraction and in situ analysis

This paper presents a hollow, silicon microneedle array, integrated with fluidic microchannels for the extraction and analysis of biofluids from just beneath the skin´s surface. This microinstrument is the first known to have been reported to successfully demonstrate the transdermal extraction of human interstitial fluid (ISF) using only capillary action. The needle fabrication is accomplished through a combination of dry and wet silicon etching technologies, wafer sawing, and anodic bonding to glass. The needle shape and size are controlled by independent fabrication steps enabling optimization of needle design for a wide range of applications.