Suite of microneedles developed for the inner ear. (a) Solid polymeric microneedle. (b) Solid metallic microneedle. (c) Solid polymeric microneedle for human RWM use. (d) Hollow microneedle for perilymph aspiration and direct intracochlear injection. (e) Five differently sized “crown” needles to facilitate cochlear implantation. (f) Microneedle array for opening simultaneous microperforations on the RWM. (g) A 410 µm sized “crown” needle for cochlear implantation, fabricated via 2PTE. (h) Dual-lumen microneedle for simultaneous aspiration and injection of fluids across the RWM. (Adapted with permission from Ref. [35], 2018, Ref. [37], 2020, Ref. [38], 2020, Ref. [39], 2021, Jeffrey W. Kysar, PhD and Anil K. Lalwani, MD).