Hollow microcoils made possible with external support structures manufactured with a two-solvent process

We present a process to manufacture solenoidal microcoils with external support structures, which leaves the space within the coil windings free. The manufacturing procedure is based on a two solvent approach (water and acetone), for selectively etching polyvinyl alcohol and polymethyl methacrylate. Two sets of microcoils were manufactured with an inner diameter of 1.5 mm, an interwinding pitch of 100 μm and five or eight coil windings respectively. The coils were designed for application in magnetic resonance imaging and spectroscopy, and characterised in a 9.4 T MR scanner. An NMR spectrum of water and MR images in receive only and transceive mode were acquired as proof of concept.