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!