Rectilinear Biphasic Waveform Control for Smaller Defibrillator Capacitors
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Solution Overview
Problem
Conventional defibrillators require larger capacitors to accommodate voltage droop and varying patient impedances, leading to inefficient energy utilization and increased size and weight, particularly in portable devices.
Innovation Solution
Employing a boost converter to control and regulate constant current delivery through an inductor, combined with an H-bridge circuit to manage energy flow in biphasic waveforms, ensuring maximum power levels are not exceeded and optimizing capacitor size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a larger capacitor is used to accommodate voltage droop and varying patient impedances, then energy delivery reliability is improved, but device weight and size increase
Solution Approach 1:
The patent implements a dynamic capacitor sizing approach where the capacitor is sized for the maximum expected impedance (e.g., 200Ω) rather than accommodating all lower impedances. The system dynamically adapts by using real-time impedance sensing and control algorithms to adjust the energy delivery parameters (voltage, current, pulse duration) based on the actual patient impedance, eliminating the need for oversized capacitors while maintaining reliable energy delivery across all impedance ranges.
Solution Approach 2:
The system changes operational parameters (voltage, current, pulse width) based on detected patient impedance to optimize capacitor utilization. By adjusting these parameters in real-time, the system ensures reliable energy delivery without requiring the capacitor to be oversized for worst-case scenarios, thereby reducing device weight while maintaining reliability.
2Reliability
If a larger capacitor is used to accommodate voltage droop, then energy delivery consistency is improved, but energy utilization efficiency deteriorates
Solution Approach 1:
The system dynamically adjusts energy delivery parameters based on real-time impedance sensing, optimizing capacitor discharge characteristics for each patient. This dynamic adaptation ensures consistent energy delivery to the patient while maximizing the utilization of stored capacitor energy, avoiding the waste associated with oversized capacitors that cannot be fully discharged.
Solution Approach 2:
The patent incorporates real-time impedance sensing and feedback control mechanisms that monitor capacitor voltage and patient impedance during energy delivery. This feedback allows the system to adjust delivery parameters to maintain consistent energy transfer efficiency, ensuring the capacitor is fully utilized without excessive voltage droop or energy waste.
3Object-affected harmful factors
If excess energy is dissipated through a resistor network, then safe power levels are maintained, but device complexity and component count increase
Solution Approach 1:
The patent removes the dissipation resistor network from the system entirely. Instead of using resistors to burn off excess energy, the system uses impedance sensing and control algorithms to precisely match energy delivery to patient needs, eliminating the need for complex passive safety components while maintaining power level safety through active control.
Solution Approach 2:
The system replaces the passive mechanical/resistive approach to power limiting with an active electronic control system. By using impedance sensing and programmable power delivery, the system achieves power safety through software-controlled algorithms rather than physical resistor networks, significantly reducing device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Reduces capacitor size and weight by 20% while maintaining energy delivery efficiency, eliminating the need for dissipation resistors and thermal management, and allowing for versatile therapeutic waveforms.
Implementation Method 1
storing a quantity of energy substantially equal to and without substantially exceeding the therapeutic quantity of energy on a capacitor
Implementation Method 2
releasing a portion of the stored energy from the capacitor into an inductor; releasing the portion of the stored energy from the inductor into the load
Data Source
AI summary
A system to deliver therapeutic energy to a patient, the system including a storage capacitor configured to store and release the therapeutic energy, a boost converter circuit coupled to the storage capacitor, and a current flow control circuit coupled to the boost converter circuit and including a plurality of control circuits configured to control a current output from the current flow control circuit in a therapeutic biphasic voltage waveform upon release of the therapeutic energy from the storage capacitor, wherein the therapeutic biphasic voltage waveform includes a ramped increase in voltage from approximately zero volts to a desired therapeutic voltage level over a time interval greater than 1 millisecond and less than a time associated with a phase switch.