Novel 3D-printed hollow microneedles facilitate safe, reliable, and informative sampling of perilymph from guinea pigs

•3D-printed microneedles perforated the round window membrane and aspirated 1 µL of perilymph.•Hearing thresholds were not affected, and microneedles were not damaged.•Perforations introduced into the round window membrane healed within 72 h.•The aspirated perilymph was of a volume and quality sufficient for proteomic analysis.