A novel microneedle device for controlled and reliable liquid biopsy of the human inner ear

Sensorineural hearing loss is the most common sensory deficit worldwide, yet our understanding of the underlying pathophysiology is limited by the challenges of access to the inner ear in a safe and reliable manner. We present a novel microneedle device for trans-round window membrane liquid biopsy, which utilizes controlled depth of perforation and microliter aspiration control to safely biopsy fluids of the inner ear. Of eleven devices tested in fresh frozen human temporal bones, seven demonstrated alignment between electrical, visual and tactile detection of round window membrane perforation, and nine were successful in aspiration of meaningful diagnostic samples from the perilymphatic space. Purity of the average perilymph sample was 69% for a 5 μL sample volume, equivalent to 3.5 μL attributable to perilymph. Diagnostic success was shown both by transmastoid facial recess and transcanal tympanotomy approach. This device can enable new advances in the understanding of inner ear pathology, and brings us one step closer to liquid biopsy of the inner ear becoming a routine part of clinical care.