Development and in-vitro characterization of an implantable flow sensing transducer for hydrocephalus.
An implantable transducer for monitoring the flow of Cerebrospinal fluid (CSF) for the treatment of hydrocephalus has been developed which is based on measuring the heat dissipation of a local thermal source. The transducer uses passive telemetry at 13.56 MHz for power supply and read out of the measured flow rate. The in vitro performance of the transducer has been characterized using artificial Cerebrospinal Fluid (CSF) with increased protein concentration and artificial CSF with 10% fresh blood. After fresh blood was added to the artificial CSF a reduction of flow rate has been observed in case that the sensitive surface of the flow sensor is close to the sedimented erythrocytes. An increase of flow rate has been observed in case that the sensitive surface is in contact with the remaining plasma/artificial CSF mix above the sediment which can be explained by an asymmetric flow profile caused by the sedimentation of erythrocytes having increased viscosity compared to artificial CSF. After removal of blood from artificial CSF, no drift could be observed in the transducer measurement which could be associated to a deposition of proteins at the sensitive surface walls of the packaged flow transducer. The flow sensor specification requirement of +-10% for a flow range between 2 ml/h and 40 ml/h. could be confirmed at test conditions of 37 degrees C.
Codman Neuro Sciences sarl, Rue Girardet 29, 2400, Le Locle, Switzerland.
Toralf
T
Bork
Andreas
A
Hogg
Markus
M
Lempen
Daniel
D
Müller
Damien
D
Joss
Thibaut
T
Bardyn
Philippe
P
Büchler
Herbert
H
Keppner
Stephan
S
Braun
Yanik
Y
Tardy
Jürgen
J
Burger
D002138:Calibration; D002151:Calorimetry; D002556:Cerebrospinal Fluid Proteins / Q000378:metabolism; D002557:Cerebrospinal Fluid Shunts; D006801:Humans; D006849:Hydrocephalus / Q000134:cerebrospinal fluid* / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery; D007700:Kinetics; D019736:Prostheses and Implants; D013686:Telemetry; D014159:Transducers
D002556:Cerebrospinal Fluid Proteins