Packaging Development of an Implantable Intracranial Pressure Catheter

Recent studies have demonstrated the intracranial pressure (ICP) monitoring is an important tool for cerebral perfusion pressure (CPP) calculation and cerebral blood flow (CBF) assessment, reducing significantly the mortality statistics. Traumatic brain injury (TBI), several others pathologies and neurosurgery conditions have been using the ICP monitoring technique. With the waves of the microelectronics and microelectromechanical systems (MEMS) industry evolution, it was possible to put the transducer and all the electronics inside the catheter tip, allowing a less invasive monitoring and decreasing the risk of infection. The state of art catheters with micro transducer on the tip can be divided into three groups: strain-gauge, optical fiber and pneumatic. Each group has its own characteristics, however the strain-gauge based has been demonstrated to be a robust solution, reliable, cost effective and with sufficient accuracy. In the present work, it was developed a strain-gauge micro transducer implantable catheter for intracranial pressure monitoring. The packaging processes adopted were the standard used by the semiconductor industry, however considering application special requirements, several process parameters and assemblage was adapted to the geometry and materials used (i.e. biocompatible) as well as, taking in consideration low volume production of medical devices. The prototypes assembled showed variations on the zero drift test. The temperature drift was 0,63 and 0,89 cmH₂O/°C and the accuracy, ±1 cmH₂O.