In order to accurately diagnose respiratory dysfunction, a physician can resort to the assessment of the electrical activity of the diaphragm (diaphragm electromyogram – EMGdi) and to its physical strength (trans- diaphragmatic pressure Pdi).
We are proposing a new catheter mounted system combining the assessment of the EMGdi and the Pdi. The system is based on two silicon micro machined pressure sensors (micro electromechanical systems – MEMS) and a new esophageal electrode geometry. The new electrode is intended to naturally filter the cardiac artifact without the use of complex mathematical techniques currently employed. Signal processing and digitizing are madelocally to minimize noise injection. Data is transferred via a high bandwidth 2,4GHz BluetoothTM wireless connexion. The entire systems must be integrated in a 5mm diameter catheter.
Electro-magnetic simulations of the new electrodes have shown good results in relation with the cardiac artifact rejection. A MEMS piezoresistive pressure sensor has been realized in 1,5um CMOS technology. A prototype of catheter including the new electrodes has been made in order to validate the results obtained in simulation.
The new catheters will be tested on humans in order to compare with the present model. The low noise data acquisition system is being designed with 0,18um CMOS and according to the latest noise reduction techniques. A bonding method is being tested in order to attach the silicon pressure sensors over the flexible printed board circuit required in an application such as a catheter.
