Acoustic emission apparatus methods for detecting termite infestation including a probe and signal processing circuitry. Image pixels on film are translated into electrical signals by photosensitive detectors. The transparent conductive thin film may have a surface nano-scale patterned by wet-etching and then annealing without using a mask for improving the light extraction rate. The towable sweeping apparatus also includes a drive motor inter-operably connected to the impeller and a bin arranged to receive debris collected by the impeller.