MEMS Infrared Emitter Modulation via Shape Change
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Solution Overview
Problem
Current infrared emitters for spectroscopy applications face limitations in high-frequency modulation and broad-spectrum emission, often requiring complex and costly setups with limited modulation bandwidth and poor signal-to-noise ratios.
Innovation Solution
A modulatable infrared emitter using a MEMS heating element with an actuator that changes its shape and/or structure to vary the emission area to total area ratio, enabling high-frequency modulation of infrared radiation without thermal time constant limitations, allowing for a compact, low-cost, and robust design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If direct modulation by varying the current supply is used, then the emission intensity can be changed, but the modulation frequency is limited by thermal time constants and device life is significantly degraded
Solution Approach 1:
The heating element is designed as a movable MEMS structure that can dynamically change its emission surface area by moving between retracted and extended positions. This mechanical dynamic adjustment allows intensity modulation without thermal time constant limitations, achieving high-frequency modulation while preserving device life.
Solution Approach 2:
The patent replaces the thermal modulation mechanism (varying current supply) with a mechanical modulation mechanism (moving the heating element to change emission area). This substitution eliminates the thermal time constant bottleneck and reduces stress on the heating element, thereby extending device life.
2Speed
If external modulation through spinning chopper wheels is used, then faster modulation is achieved, but the setup becomes costly and less compact and robust
Solution Approach 1:
The modulation function is merged directly into the infrared emitter by integrating the movable heating element with the emission source. This eliminates the need for separate external chopper wheels and associated mechanical structures, resulting in a compact, robust, and cost-effective solution.
Solution Approach 2:
Instead of using a rotating chopper wheel that modulates the beam in space, the patent modulates the emission area in the planar dimension by moving the heating element forward and backward. This dimensional approach simplifies the mechanical system while achieving the same modulation effect.
3Speed
If narrowband laser sources are used, then high radiation intensities and high-frequency modulation are achieved, but only molecules with matching absorption spectrum are detectable and the cost is relatively high
Solution Approach 1:
The heating element is designed to emit broadband infrared radiation that covers a wide spectral range, making the emitter universally applicable for detecting multiple different gas molecules with different absorption spectra. The movable structure provides multi-functionality by enabling both broadband emission and high-frequency modulation in a single device.
4Adaptability or versatility
If thermal broadband emitters are used, then a wide spectrum is achieved, but the modulation frequency is limited and direct modulation degrades device life
Solution Approach 1:
The heating element is designed as a movable MEMS structure that can dynamically change its emission surface area by moving between retracted and extended positions. This mechanical dynamic adjustment allows intensity modulation without thermal time constant limitations, achieving high-frequency modulation while preserving device life.
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 achieves high-frequency modulation with a broad spectrum of infrared radiation, enhancing signal-to-noise ratios and extending device life, suitable for applications like photoacoustic spectroscopy with improved durability and compactness.
Implementation Method 1
a heating element, in particular a MEMS heating element (3) comprising heatable regions (7) for emitting infrared radiation
Implementation Method 2
the projection of the heatable regions (7) in the emission direction (29) forming an emission area (10)
Data Source
AI summary
The invention relates to a modulatable infrared emitter comprising a MEMS heating element and an actuator, wherein the actuator triggers shape and/or structure changes of the MEMS heating element. Said change in shape and/or structure of the MEMS heating element may vary the ratio of the emitting area to the total area, thereby producing a change in intensity of the emitted infrared beam. The invention further relates to a manufacturing method for the infrared emitter, a method for modulated emission of infrared radiation using the infrared emitter, and preferred uses of the infrared emitter. In further preferred aspects the invention relates to a system comprising the infrared emitter and a control device for regulating the actuator.