A series of optical spectral sensors for gas and vapor measurements using a combination of solid-state light sources (LED or Broadband) and multi-element detectors, housed within an integrated package that includes the interfacing optics and acquisition and processing electronics. The sensor is designed to be produced at a low cost and capable of being fabricated for mass production. Spectral selectivity is provided by a custom detector eliminating the need for expensive spectral selection components. A multi-component gas monitor system may have no moving parts and the gas sample flows through a measurement chamber where it interacts with a light beam created from the light source, such as a MEMS broad band IR source or a matrix of LEDs. A custom detector(s) is/are configured with multi-wavelength detection to detect and measure the light beam as it passes through the sample within the measurement chamber.