Abstract: An apparatus for housing a submergible optical sensor is provided. The apparatus comprises a sensor body having a sensor opening. The sensor body is operable to protect a sensor when submerged in a fluid. A shutter is disposed above the sensor opening. A motor couples to the shutter and can rotate the shutter. A controller couples to the motor and is operable to cause the motor to rotate the shutter such that the sensor opening is exposed when the sensor takes a measurement. The controller is further operable to cause the motor to rotate the shutter such that the shutter covers the sensor opening when the sensor is not taking a measurement.

Abstract: A modular water quality measurement apparatus and method includes a sealed or unsealed housing with a universal sensor interface cap (12) and mechanical and electrical sensor connections (14) for receiving removably attachable sensors (16 or 16'). Each of the mechanical and electrical sensor connections (14) are individually electrically connected to a programmable motherboard (20) within the housing. Sensor daughterboards (22) are removably attached to the motherboard (20) corresponding to individual sensors (16 or 16') connected to the universal sensor interface cap (12). Further, removably attachable input/output daughterboards (24) are electrically connected to the motherboard (20) for accommodating various serial interface types and software is provided for collecting information from the sensors (16 or 16') and transmitting the information through the input/output daughterboards (24) for manipulation by a user.

Abstract: A method and an apparatus for measuring concentration of a dissolved substance are disclosed. In accordance with the method, measurements are made with two instruments having different permeability characteristics to obtain two readings, and these readings are corrected in accordance with a pre-determined relationship. The apparatus provides an electrochemical cell wherein a common anode is surrounded by closely-spaced cathodes. The cathodes are in at least two groups, wherein the first group has a first response characteristic to the dissolved substance and the second group has a second response characteristic. In the preferred embodiment, the two characterisitcs are produced by providing different distances between a substance-selective membrane and respective cathodes. In one embodiment, the cathodes are annular and surround the anode at different radii, while in another embodiment the cathodes are discrete and are spaced from the anode by equal distances.