Effective field monitoring systems are needed to improve the quality and increase the use of environmental monitoring. Most laboratory-based systems, although powerful tools for the laboratory analyst, are not well-suited for field applications. Continuous, in-situ sensors provide real time data with high accuracy and low cost for multiple analyses. Optical sensor technologies are highly accurate and sensitive, are capable of being used in-situ and are highly versatile in terms of their potential applications. Fiber Optic Chemical Sensors (FOCSTM) utilize the characteristics of optical sensors to provide an effective tool for continuous environmental monitoring. The FOCSTM technology has recently been adapted to a new platform: a chip-level, solid state, optical waveguide, chemical sensor. This new optical platform provides several advantages of the FOCSTM, and further improves the effectiveness of optical sensors for environmental monitoring. The chip-level optical sensor platform has been used with different optical sensing mechanisms (e.g., refractive index, absorbance and fluorescence) for the detection of hydrocarbons, carbon monoxide, oxygen and pesticides.