Miniaturised Infrared Spectrophotometer for Low Power Consumption Multi-Gas Sensing

Area of Science:

• Optical Engineering
• Environmental Monitoring
• Spectroscopy

Background:

• Miniaturization of analytical instruments is crucial for portable sensing applications.
• Mid-infrared spectroscopy offers selective detection of various gases based on their absorption spectra.
• Developing low-power, multi-gas sensors requires integration of advanced optical and microelectronic components.

Purpose of the Study:

• To describe the concept, design, and implementation of a miniaturized spectrophotometer for multi-gas sensing.
• To evaluate its performance as a low-power, mid-infrared gas sensor.
• To explore the use of different optical filters and pulsed operation for enhanced efficiency.

Main Methods:

• Designed and constructed a miniaturized spectrophotometer using a lead selenide photo-detector array and MEMS micro-hotplate.
• Employed an injection-molded Schwarzschild optics configuration with pass band filters for spectral discrimination.
• Investigated both fixed-line and linear variable optical filters, alongside short-time pulsed source inputs.
• Utilized a distinct reference channel for gas measurements and employed modeling for optimization.

Main Results:

• The spectrophotometer effectively detected multiple gases including carbon dioxide, carbon monoxide, and methane within the 2.9-4.8 µm range.
• Low-power consumption was achieved through short-time pulsed operation.
• Performance was optimized considering component efficiency, power usage, and temperature sensitivity.
• The sensor demonstrated effectiveness as a stand-alone single and multi-gas detector.

Conclusions:

• The developed miniaturized spectrophotometer is a viable low-power solution for stand-alone single and multi-gas sensing.
• Optimized optical filters and pulsed operation enhance sensor efficiency and reduce power consumption.
• This technology holds potential for portable environmental monitoring and industrial gas analysis.