| Low-Cost Surface Mount LED Gas Sensor |
| Date: | October 2005 |
| MERL Contact: | William Yerazunis |
| Author: | Roderick L. Shepherd, William S. Yerazunis, King Tong Lau, Dermot Diamond |
| Where Published: | IEEE Sensors Journal |
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. |
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