Abstract: A sensor device includes an elongated housing containing particle motion sensors spaced apart along a longitudinal axis of the elongated housing, where the elongated housing has a length that is greater than a width of the elongated housing. A second portion includes communication circuitry to communicate over a communication medium, the second portion coupled to the elongated housing and having a width that is greater than the width of the elongated housing.

Abstract: A method of determining information inside a borehole is provided. The method includes the use of a ferrofluid seal to seal a rotating shaft used in the borehole. In preferred embodiments, the method comprises: selecting at least one sensor to be lowered into the borehole; coupling the sensor to the end of a rotating shaft; running the rotating shaft through a housing including a plurality of bearings and an oil reservoir, sealing a downhole end of the housing from an exterior of the housing with a ferrofluid seal; and forcing the sensor, rotating shaft, housing, bearings, oil reservoir, and ferrofluid seal into the borehole to make a measurement.

Abstract: A sensor device includes an elongated housing containing particle motion sensors spaced apart along a longitudinal axis of the elongated housing, where the elongated housing has a length that is greater than a width of the elongated housing. A second portion includes communication circuitry to communicate over a communication medium, the second portion coupled to the elongated housing and having a width that is greater than the width of the elongated housing.