Fast Recovery Diode Pulse Generator for 3 ns Cell Electroporation
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Solution Overview
Problem
Existing pulse generators for electroperturbation of biological cells are limited by their size, repetition rate, pulse duration, and jitter, with spark gap switched transmission lines being physically large and having low repetition rates, and MOSFET switched capacitors unable to generate pulses narrower than 15-20 ns due to circuit limitations.
Innovation Solution
A pulse generator circuit utilizing a diode as an opening switch with a saturable core transformer and a switching system that changes the tank circuit's admittance, allowing for pulses of no more than 3 nanoseconds and 1 kilovolt amplitude at a frequency of at least 100 kHz, using a MOSFET and diode array to achieve fast switching and high voltage delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If spark gap switched transmission lines are used to generate ultra-short pulses, then pulse amplitude and speed are improved, but device size and repetition rate are worsened
Solution Approach 1:
The patent replaces the mechanical spark gap switching system with an electronic switching system using MOSFETs and fast recovery diodes. This substitution eliminates the need for large transmission lines and physical spark gaps, achieving ultra-fast rise times (less than 100 picoseconds) while dramatically reducing device size and enabling high repetition rates (greater than 100 kHz).
Solution Approach 2:
The patent changes the operating parameters by using fast recovery diodes with reverse recovery times less than 100 picoseconds and MOSFETs with switching times less than 50 picoseconds. These parameter changes enable the generation of pulses with rise times less than 100 picoseconds while maintaining compact device dimensions and high repetition rates.
2Volume of moving object
If MOSFET switched capacitors are used to generate ultra-short pulses, then device size is reduced, but pulse duration control is worsened
Solution Approach 1:
The patent implements dynamic control of the switching system by precisely controlling the gate voltages of MOSFETs and the biasing of fast recovery diodes. This dynamic control enables independent adjustment of pulse width (from less than 100 picoseconds to several nanoseconds) and amplitude, overcoming the static limitations of traditional MOSFET switched capacitor circuits while maintaining compact size.
Solution Approach 2:
The patent employs periodic switching of MOSFETs and fast recovery diodes to generate repetitive ultra-short pulses with controllable width. By optimizing the switching timing and duration, the system can produce pulses with widths less than 100 picoseconds at repetition rates greater than 100 kHz, achieving both compact size and precise pulse duration control.
3Ease of manufacture
If conventional switching devices are used, then ease of manufacture is improved, but pulse precision and jitter are worsened
Solution Approach 1:
The patent creates a composite switching system combining MOSFETs with fast recovery diodes, where each component complements the other's strengths. The MOSFETs provide fast turn-on capability with low jitter, while the fast recovery diodes provide rapid turn-off with minimal reverse recovery time. This composite approach achieves pulse precision with jitter less than 10 picoseconds while maintaining ease of manufacture using standard semiconductor fabrication processes.
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
The solution enables the generation of extremely short, high-amplitude pulses with high frequency and low jitter, effectively manipulating biological cells without adverse effects on the cell membrane, allowing for precise cell biology research and manipulation.
Implementation Method 1
A pulse generator circuit may include a diode configured to operate as an opening switch and that saturates in less than 100 nanoseconds
Implementation Method 2
a tank circuit in series with the diode having an admittance that is switchable from a first value to a second value that is different from the first value
Implementation Method 3
a saturable core transformer configured to operate as a switch that controls the opening of the diode
Implementation Method 4
Ultra-short, high-field strength electronic pulses may be used in the electroperturbation of biological cells
Data Source
AI summary
A pulse generator circuit may include a diode configured to operate as an opening switch, a tank circuit in series with the diode having an admittance that is switchable from a first value to a second value that is different from the first value, and a switching system configured to cause the tank circuit to switch between the first value and the second value. The diode may saturate in less than 100 nanoseconds. A saturable core transformer may operate as a switch that controls the opening of the diode. The pulse generator may generate a plurality of pulses, each having a length of no more than 3 nanoseconds and an amplitude of at least 1 kilovolt. Electrodes may be connected to the pulse generator to deliver the plurality of pulses to biological cells.