Cerebrospinal fluid (CSF) is a water-like fluid produced in the brain that circulates around and protects the brain and spinal cord. It is believed that CSF is absorbed into the superior sagittal sinus through biologic one-way valves called arachnoid villi, which are located in dura mater. Hydrocephalus is an abnormal accumulation of CSF within the subarachnoid space of the brain due to impaired CSF absorption. Hydrocephalus is one of the most frequently encountered problems in Neurosurgery. Currently, hydrocephalus is treated by a surgical procedure, performed by a neurosurgeon, in which a tube called a shunt is placed into the patient's body. The shunt systems for diverting CSF from the intracranial compartment was developed in 1960`s and has remained essentially unchanged for the last 40 years. In this project we attempt to replace the deficient arachnoid villi (AV) that produce the pathologic condition of communicating hydrocephalus with a micro-fabricated device to restore the normal absorptive function. The microfabricated arachnoid villi (MAV) will be implanted against the dura mater.