BLOOD PRESSURE BIOMEDICAL ENGINEERING TAE_EUI, KIM
Invasive BP measurement Catheter Dome Diaphragm Strain gages (usually Four) Pressure Sensor Po should be same as Pi “Fluid Mechanics”
What affect the quality of Po Catheter length should be shorter but there is Viscosity of liquid Diameter Elastic material for catheter Diaphragm itself should be elastic No air bubble
Equivalent Circuit Method of Catheter – Sensor System Electric CircuitFluid Mechanics Voltage, V [v]Pressure, P [pa] Current, i [A](Volume) Flow, f [m3/s] Charge, q [c]Volume, V [m3] R, L, C circuitPhysics things
Equivalent Circuit Method of Catheter – Resistance Electrical resistance : Liquid resistance : If viscosity is too big?
Equivalent Circuit Method of Catheter – Capacitance or Compliance ( AC flow ) The bigger Compliance, the bigger flow
Equivalent Circuit Method of Catheter – Inductance or Innertance
Equivalent Circuit Model Catheter Sensor
Equivalent Circuit Model Catheter & Sensor are rigid but not diaphragm
Equivalent Circuit Model
Frequency Transfer Function
Magnitude Response
Phase Response
Reference
Steady State Frequency Response
; Principle of Superposition
Transient Response ; Principle of Superposition Transient Property! Transient Property!