an inexpensive and rapid method for fabricating arrays of hollow microneedles uses a photoetchable glass . furthermore , the glass hollow microneedle array can be used to form a negative mold for replicating microneedles in biocompatible polymers or metals . these microneedle arrays can be used to extract fluids from plants or animals . glucose transport through these hollow microneedles arrays has been found to be orders of magnitude more rapid than natural diffusion .