An implantable hydrogel check valve for hydrocephalus treatment—development and in vitro measurements

Permanently stable cerebrospinal fluid (CSF) draining devices are needed for treating hydrocephalus, a debilitating brain disorder. Currently implemented shunts are unreliable as long term implants primarily due to their largely protracted form. The proposed hydrogel valve attempts to generate greater permanency as a chronic implant by forming a direct CSF channel across the physiologically blocked natural valve formations, the arachnoid granulations (AG), and restoring near-natural CSF draining operations. In this way, all CSF draining operations are confined within the cranium. The valve relies on innate hydrogel swelling phenomenon to strengthen reverse flow sealing at idle and negative pressures. In vitro measurements in emulated CSF solutions display operation spanning targeted range of normal healthy draining (cracking pressure, P_T ~ 1 – 110 mmH₂O and outflow hydraulic resistance, R_h ~ 24 – 152 mmH₂O/mL/min), with negligible reverse flow leakage. Overtime tests demonstrate the valve’s operational reproducibility and in situ feasibility, substantiating its potential for use as a permanent implant.