Dynamic Biasing of Ion Optics in Mass Spectrometers
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Solution Overview
Problem
Current laser desorption and ionization mass spectrometers (LDI-MS) are costly due to the need for separate voltage sources for each ion optic element, which increases the expense and complexity of the instrument without necessarily improving sensitivity.
Innovation Solution
A circuit and method that dynamically generates a steady state voltage bias between the ion source and extraction elements using a single pulse generating power supply, allowing for control of the voltage bias through pulse characteristics such as amplitude, width, and repetition rate, eliminating the need for separate voltage sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If separate voltage sources are used for each ion optic element, then full control of voltages is achieved, but instrument cost and complexity increase
Solution Approach 1:
The patent combines multiple voltage source functions into a single voltage source by using a pulsed voltage output that dynamically generates different voltage biases for the source and extraction elements. The pulser generates pulses that are capacitively coupled to the extraction element, creating a time-varying voltage distribution that provides both source and extraction voltage control through one device.
Solution Approach 2:
The patent uses dynamic pulsed voltage generation to create different steady-state voltage biases on different ion optic elements at different times. By controlling the pulse characteristics (amplitude, width, repetition rate), the system dynamically generates the required voltage distribution without needing separate static voltage sources for each element.
2Measurement precision
If multiple voltage sources are used, then precise voltage control is improved, but expense of the instrument increases
Solution Approach 1:
The single voltage source is designed to perform multiple functions: it generates the base voltage for the source element, creates pulsed extraction voltages, and dynamically generates intermediate voltage biases on extraction elements. This multi-functional approach eliminates the need for multiple expensive voltage sources while maintaining precise voltage control through pulse parameter adjustment.
Solution Approach 2:
The patent controls the output voltage bias by changing parameters of the pulsed voltage signal, specifically pulse width, pulse amplitude, and pulse repetition rate. By varying these temporal parameters, the system achieves precise control over the effective voltage bias without requiring multiple voltage sources with different output levels.
3Object-affected harmful factors
If grids are used in ion optic apertures, then electric field penetration is limited, but ion optics performance degrades due to ion collisions
Solution Approach 1:
The patent applies dynamic pulsed voltage extraction where the extraction element voltage is rapidly switched on only when needed for ion extraction. During the pulse-off period, the extraction element voltage returns to a lower level, reducing field penetration through the aperture. This time-varying approach allows grid-free apertures to function effectively by minimizing continuous field penetration while maintaining extraction capability during pulses.
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
This approach reduces the cost of the mass spectrometer by using a single power supply and improves sensitivity by allowing for a field-free region during ionization, enhancing ion detection without compromising performance.
Implementation Method 1
a pulse generator capacitively coupled with the second ion optical element
Implementation Method 2
a second ion optical element resistively coupled with the first ion optical element
Implementation Method 3
a laser, which directs pulses of laser light at the sample, desorbing analyte molecules from the probe surface
Implementation Method 4
desorbing analyte molecules from the probe surface and ionizing them
Data Source
AI summary
A device for dynamically biasing an ion optic element, for example, in a mass spectrometer. The device includes a voltage source, a first ion optical element coupled with the voltage source, a second ion optical element resistively coupled with the first ion optical element; and a pulse generator capacitively coupled with the second ion optical element. The pulse generator is configured to apply a series of pulses to the second ion optical element. In steady state operation, a dynamic voltage bias is generated between the first ion optical element and the second ion optical element. The dynamic voltage bias is controllable by controlling the characteristics of the applied pulses, such as the pulse width, pulse amplitude, and pulse repetition rate of the applied pulses.