A sensor for determining at least one characteristic of at least one substance, the sensor including: at least one array, each array including a plurality of acoustic transducers with a proximal-most transducer and a distal-most transducer; a controller: for controlling each transducer to be selectively in a generation mode for generating an analysis signal, or a reception mode for receiving an analysis signal transmitted through and/or reflected from one or more of the plurality of substances to produce an output signal, and, for controlling the sensor to perform scans of the at least one array, each scan having a plurality of scan steps, such that, during each scan step, at least one transducer from any of the at least one array is in the generation mode and at least one other transducer from any of the at least one array is in the reception mode; and a processor for processing one or more signals receivable from one or more of the controller, a transducer in generation mode and a transducer in reception mode to determine the at least one characteristic from the one or more signals, the sensor being characterized in that the at least one array is a linear array of transducers and the controller is further adapted to control each scan step such that two transducers in reception mode are adjacent to at least one transducer in generation mode with one of the transducers in reception mode on a proximal side of the at least one transducer in generation mode and the other transducer in reception mode on a distal side of the at least one transducer in generation mode. at least one array, each array including a plurality of acoustic transducers with a proximal-most transducer and a distal-most transducer; a controller: for controlling each transducer to be selectively in a generation mode for generating an analysis signal, or a reception mode for receiving an analysis signal transmitted through and/or reflected from one or more of the plurality of substances to produce an output signal, and, for controlling the sensor to perform scans of the at least one array, each scan having a plurality of scan steps, such that, during each scan step, at least one transducer from any of the at least one array is in the generation mode and at least one other transducer from any of the at least one array is in the reception mode; and a processor for processing one or more signals receivable from one or more of the controller, a transducer in generation mode and a transducer in reception mode to determine the at least one characteristic from the one or more signals, the sensor being characterized in that the at least one array is a linear array of transducers and the controller is further adapted to control each scan step such that two transducers in reception mode are adjacent to at least one transducer in generation mode with one of the transducers in reception mode on a proximal side of the at least one transducer in generation mode and the other transducer in reception mode on a distal side of the at least one transducer in generation mode. for controlling each transducer to be selectively in a generation mode for generating an analysis signal, or a reception mode for receiving an analysis signal transmitted through and/or reflected from one or more of the plurality of substances to produce an output signal, and, for controlling the sensor to perform scans of the at least one array, each scan having a plurality of scan steps, such that, during each scan step, at least one transducer from any of the at least one array is in the generation mode and at least one other transducer from any of the at least one array is in the reception mode; and a processor for processing one or more signals receivable from one or more of the controller, a transducer in generation mode and a transducer in reception mode to determine the at least one characteristic from the one or more signals, the sensor being characterized in that the at least one array is a linear array of transducers and the controller is further adapted to control each scan step such that two transducers in reception mode are adjacent to at least one transducer in generation mode with one of the transducers in reception mode on a proximal side of the at least one transducer in generation mode and the other transducer in reception mode on a distal side of the at least one transducer in generation mode.