Polyvinylidene fluoride (PVDF) piezoelectric nanofibers were fabricated through near-field electrospinning (NFES) to develop a flexible piezoelectric element. Innovative screen printing technology was employed to produce bend-type electrodes designed with d 33 mode patterns. The electrodes and PVDF nanofibers were then attached to a polyimide film substrate. Compared with piezoelectric ceramics, piezoelectric fibers are inexpensive, flexible, and highly biocompatible. They also have a higher electron density than piezoelectric films, indicating that they are more efficient in electromechanical conversion. Thus, in this study, we adopted piezoelectric fibers to create a displacement sensor with bend-type electrodes that employed optimized pattern designs to increase the efficiency of piezoelectric conversion and sensitivity. The experimental results revealed that the type of electrode was critical for enhancing output voltage. The novel bend-type electrodes induced an average positive voltage of 960.5 mV during a tapping experiment, increasing the maximum voltage by 59.74% compared with a series-type electrode. The positioning accuracy of the displacement sensor was 600 μm; thus, the sensor could successfully determine positioning, confirming the feasibility of the displacement sensing mechanism.

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In this paper, we propose a process inspection framework for metal additive manufacturing (AM) processes. AM, also known as 3D printing, is the process of joining materials to make objects on the basis of 3D model data and is envisioned to play a strategic role in maintaining economic and scientific dominance. Different from conventional manufacturing methods, the AM process is a point-by-point and layer-by-layer manufacturing. Thus, there are many opportunities to generate a process error that can cause quality issues in an AM part. A systematic AM process inspection is needed to yield acceptable performance of the part. The critical parameters that may affect the part quality are identified before processing, during processing, and after processing. The framework of the initial AM process inspection is presented. By using basic sensors, such as a microhardness tester and profilometer, we can obtain critical information about an additive manufactured part. Engineering

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