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Flexible energy harvesters have become a research hotspot in both academia and industry because of their great advantages in powering wearable electronic devices. The flexible energy harvesters based on piezoelectric materials are recognized as a competitive method because of their sensitivity to mechanical deformation, excellent energy conversion performance, mature production technology and simple structure. This paper presents a comprehensive review to illustrate the research progress and future development of wearable flexible piezoelectric harvesters. In this work, the widely-used piezoelectric materials for flexible energy harvesters, including inorganic piezoelectric materials, organic piezoelectric materials and piezoelectric composites, are first summarized. The research progress on the influence of ceramic content, morphology, distribution, surface chemical modification, and the addition of conductive materials on the properties of piezoelectric composites are systematically discussed. Additionally, this paper also presents novel structures and fabrication methods of flexible piezoelectric energy harvesters. 1 Finally, future trends in research, development and innovation of flexible piezoelectric energy harvesters are outlined and prospected.

This study presents laser stripe center extraction algorithm for desktop-level 3D laser scanners. The laser stripe center extraction accuracy is an important factor affecting 3D scanning result. Desktop-level devices should have adaptability of a wide range of scanning objects. In this paper, laser stripe energy distribution characteristics with different laser stripe width, ambient light, materials and colors are obtained by experiments. Experiment results show that waveforms of bright spot, low brightness stripe and stripe with large width are complex or easily disturbed, so the center extraction algorithm of them are studied. The extraction effects of extremum method, gradient method and gray centroid method under different conditions are compared. Based on traditional grayscale value, a weighted grayscale value is proposed to extract laser stripe center. Standard deviations of extracted pixel position and fitting pixel position are calculated by different method with different weighted grayscale value. For different conditions, especially for different ambient light intensity, weight matrix plays an important role to extraction result.