Semiconductor Membrane Molecule Detector via Phonon Field Emission
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Solution Overview
Problem
Current mass spectrometry detectors face limitations in detecting large molecules due to signal intensity fall-off with increasing mass, particularly in MALDI or ESI methods, and require cryogenic temperatures, which are costly and impractical for routine use.
Innovation Solution
A semiconductor-based detector that utilizes field emission and secondary electron emission via phonons to detect molecules, including proteins and oligonucleotides, without the need for cryogenic temperatures, by converting kinetic energy from impacting molecules into phonons that induce electron emission from a thin electron emitting layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detectors (microchannel plates or electron multipliers) are used in mass spectrometry, then detection is feasible for small molecules, but signal intensity falls off dramatically with increasing molecular mass, limiting analysis to fragments below 100 kDa
Solution Approach 1:
The patent introduces a semiconductor membrane as an intermediary between the incoming molecular ions and the electron detector. The membrane converts the kinetic energy of impacting molecules into phonons (vibrational quanta), which then induce field emission of electrons from the semiconductor material. This intermediary conversion mechanism bypasses the limitation of direct electron multiplication, enabling detection of large molecules up to several MDa with unity detection efficiency
Solution Approach 2:
The patent replaces the conventional electron multiplication mechanism (mechanical/electrical amplification in microchannel plates) with a phonon-mediated field emission process. By substituting the detection mechanism to rely on phonon generation and field emission rather than electron cascade multiplication, the system overcomes the mass-dependent signal fall-off inherent in conventional detectors
2Measurement precision
If cryogenic calorimeters with superconducting junctions are used to detect large molecules, then high resolution and sensitivity are achieved, but the system requires operating temperatures far below 1K, increasing expense and complexity
Solution Approach 1:
The patent changes the operating temperature parameter from cryogenic (below 1K) to room temperature operation. By utilizing field emission from semiconductor materials at elevated temperatures, the system eliminates the need for complex superconducting junctions and cryogenic cooling infrastructure while maintaining high detection resolution and unity detection efficiency
Solution Approach 2:
The patent replaces expensive, complex superconducting detector systems with simpler, room-temperature semiconductor-based detectors. The semiconductor membrane and electron emitting layer can be fabricated using standard semiconductor processing techniques, eliminating the need for costly superconducting materials and cryogenic infrastructure
3Quantity of substance
If superconducting junction detectors are used, then detection of heavy proteins (several MDa) is possible, but the number of detector pixels is limited (maximal 16) and arraying is difficult due to complexity
Solution Approach 1:
The patent creates a universal detector design where the semiconductor membrane with electron emitting layer can be configured in various geometries and scaled to different sizes. The simple structure of thin semiconductor films with metal contacts allows for easy fabrication of large-area detectors and arrays, unlike the complex wire-connected superconducting pixel arrays. This enables both high mass range detection and flexible detector array configurations
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
Enables sensitive detection of large molecules up to several MDa with unity detection efficiency, maintaining sensitivity across a wide mass range and operating at room temperature, thus overcoming the limitations of existing detectors.
Implementation Method 1
The kinetic energy of molecules contacting the semiconductor membrane is transferred through the membrane via the generation of vibrational quanta (i.e. phonons)
Implementation Method 2
an electron detector, which may or may not include a means for electron amplification, is positioned to detect the emitted electrons
Implementation Method 3
generation of electrons via field emission (FE) and/or secondary electron emission (SEE) via phonons
Data Source
AI summary
An active detector and methods for detecting molecules, including large molecules such as proteins and oligonucleotides, at or near room temperature based on the generation of electrons via field emission (FE) and/or secondary electron emission (SEE). The detector comprises a semiconductor membrane having an external surface that is contacted by one or more molecules, and an internal surface having a thin metallic layer or other type of electron emitting layer. The kinetic energy of molecules contacting the semiconductor membrane is transferred through the membrane and induces the emission of electrons from the emitting layer. An electron detector, which optionally includes means for electron amplification, is positioned to detect the emitted electrons.