Manufacture of high-aspect-ratio micro-hair sensor arrays

Arrays of microposts or micropillars find a variety of applications and one of their key properties is the aspect ratio (AR) of the individual posts. This parameter, for example, determines the sensitivity of micropost force field sensors. A concept for the manufacture of arrays of micro-hairs is presented allowing us to create extremely high AR of the filiform micro-hairs. The concept is based on a 'lost mould process' allowing for frictionless de-moulding of the sensor array by melting respectively dissolution of a mould. Such a 'lost mould process' requires an inexpensive manufacture of the moulds. Moulds were thus prepared by laser drilling of wax foils. The concept has been applied to the manufacture of micro-hairs from poly(dimethylsiloxane) (PDMS) elastomers and aspect ratios close to 20 have been achieved. The basic concept is not restricted to elastomers but can be adapted to other types of materials.