Multiple parameter environment monitoring via wireless Internet of Thing sensors is growing rapidly, thanks to low power techniques of the node. More importantly, the ever more complex and highly efficient energy harvesting systems enable long-term continuous monitoring in inaccessible environments without needing to change the battery. This paper reviews existing energy harvesting modalities, including photovoltaic, piezoelectric, pyroelectric, electromagnetic, and vibration, together with circuit techniques of interfacing power management circuits for energy harvesters. Moreover, techniques used to interface with multiple mode energy harvesters to obtain a stable output power with optimal power efficiency are discussed as an emerging direction. The state-of-the-art energy harvesting systems together with future development trends are provided.

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This Special Section is dedicated to the latest trends in smart sensors for industrial applications. It has in total 26 papers, published in two parts, each consisting of 13 papers. In the Guest Editorial of Part I, published in the September 2017 issue, we validate the indispensable role sensors have in modern industry. Productivity, quality, reliability, and safety heavily depend on the performance of the sensors employed. This is because sensors form an interface between the production equipment and the surrounding environment and provide feedback based on the results of the executed operations. Consequently, sensors can be found in an extremely wide range of applications in industrial systems. Here, we introduce and briefly summarize the remaining 13 papers from this "Special Section on New Trends in Smart Sensors for Industrial Applications" of the IEEE Transactions on Industrial Electronics .@en

In modern industry, productivity, quality, reliability, and safety heavily depend on the performance of the sensors employed. They form an interface between the production equipment and the surrounding environment providing feedback based on the results of the executed operations. Thus, sensors can be found in an extremely wide range of applications in industrial systems, in which they play a very important role. The first element in any control and measurement system is the sensor itself. Sensor performance defines the performance of the control/measurement system and that of the industrial system as a whole. It is not possible to distinguish between correct and incorrect information provided by a sensor, unless additional information provided by another sensor is used. This validates the statement: No machine can perform better than its sensors.@en

This paper presents a review of the latest advances in the field of capacitive, inductive (eddy current), and magnetic sensors, for measurement of absolute displacement. The need for accurate displacement and position measurement in the micrometer, nanometer, and subnanometer scales has increased significantly over the last few years. Application examples can be found in high-tech industries, metrology, and space equipment. Besides measuring displacement as a primary quantity, absolute displacement sensors are also used when physical quantities such as pressure, acceleration, vibration, inertia, etc., have to be measured. A better understanding of the commonalities between capacitive, inductive, and magnetic displacement sensors, as well as the main performance differences and limitations, will help one make the best choice for a specific application. This review is based on both theoretical analysis and experimental results. The main performance criteria used are: sensitivity, resolution, compactness, long-term stability, thermal drift, and power efficiency.@en