Low-Cost Surface Mount LED Gas Sensor

    •  Roderick L. Shepherd, William S. Yerazunis, King Tong Lau, Dermot Diamond, "Low-Cost Surface Mount LED Gas Sensor", Tech. Rep. TR2005-097, Mitsubishi Electric Research Laboratories, Cambridge, MA, October 2005.
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      • @techreport{MERL_TR2005-097,
      • author = {Roderick L. Shepherd and William S. Yerazunis and King Tong Lau and Dermot Diamond},
      • title = {Low-Cost Surface Mount LED Gas Sensor},
      • institution = {MERL - Mitsubishi Electric Research Laboratories},
      • address = {Cambridge, MA 02139},
      • number = {TR2005-097},
      • month = oct,
      • year = 2005,
      • url = {}
      • }
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A low-cost chemical sensor comprising surface mount light emitting diodes (LEDs) has been developed for colorimetric based gas detection. The device consists of a pair of LEDs connected to a simple PIC microcontroller circuit, and in most basic form requires the use of only 2 I/O pins on the chip. The key features of this sensor are the use of an LED, rather than a phtodiode for light detection and an all-digital light detection protocol that leads to a reduction in cost and power consumption by avoiding the need for an Analog-to-Digital converter (ADC). The surface mount diodes employed are more compact than standard LEDs, and are more amenable to coating by solid-state sensor films. Results are presented from sensors employing a chemochromic ammonia sensitive film and demonstrate detection of this target in the ppm range. The configuration is applicable to a wide range of colorimetric based gas sensing materials.