This article showcases a compact self-powered contact-mode triboelectric (TE) phenomenon-based vibration sensor for predictive maintenance of industrial machinery. The sensor has a suspended proof-mass that oscillates under external vibration and causes contact-separation between Teflon and zinc oxide (ZnO) films creating tribo signals, which are used for both sensing and powering mechanisms. For these sensors to be implemented in real-time applications, the sensor must be cost-effective, reliable, and repeatable. Hence, the active layer (ZnO film) is fabricated by an efficient process of microwave-assisted thermal decomposition followed by the established screen printing method. The sensor operates up to 400 Hz and is highly robust with no significant decay in signal strength even after 120 000 cycles tested at elevated stress values. The device produces a maximum voltage (V) of ±30 V, short circuit current of ±3 µA, and can deliver a maximum power density of 0.5 W m −2 , at 8 MΩ load resistance. In the frequency domain, the device generates a maximum V at 55 Hz and can charge 1 µF capacitor to 3.5 V in 25 s. To demonstrate the functionality of the sensor in a real application, it is implemented on a lab-scale vacuum pump to capture the system faults by analyzing the harmonic signatures. Thus, in this article, we have showcased end-to-end development of the sensor from material synthesis to device testing along with its signal processing techniques and proved that the sensor can readily be implemented in industrial environments as is. This article thus emphasis bridging the lab-to-market gap for TE devices as a self-powering sensor.
Inefficient light absorption and poor charge separation are considered as two major bottlenecks for achieving highly efficient bulk heterojunction organic solar cells (BHJ OSCs). In the present study, we have introduced an additional phenyl-C71-butyric acid methyl ester (PC 70 BM) layer to modify the interface between ZnO based electron transport layer (ETL) and photoactive layer comprised of Poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thio-phene-)-2-carboxylate-2-6-diyl)] (PTB7-Th):PC 70 BM. This interface engineering has quenched the electron-hole recombination at the interface and has improved power conversion efficiency (PCE) from 6.65 to 7.74%. Devices were fabricated in an inverted geometry having a structure ITO/ZnO (40nm)/PC 70 BM (5nm)/PTB7-Th:PC 70 BM (70nm)/MoO 3 (10nm)/Ag (100nm). Additionally, V-grooved textured PDMS films were attached to the backside of OSC substrates which has further improved PCE to 9.12%. Our study suggests that the performance enhancement as observed in OSCs with V-grooved textured PDMS films could be due to increased total optical path length of the incident light within the device.
Triboelectric nanogenerators (TENGs) have marked their applications in various elds, most importantly, in medical devices. The electrical output of the TENGs mainly concentrated on parameters such as electrode separation distance, applied mechanical pressure, surface charge density, and overlapping surface-area. The surface-area of the active layer in TENGs plays a crucial role. Given this, the present contribution is the rst report on the utilization of lanthanum oxide (La 2 O 3 ) as an active material with a large surface-area (~72.33 m 2 /g) in TENGs. The nanocrystals of La 2 O 3 have been successfully embedded into TENGs architecture through a high-quality screen-printed lm with a Te on-counter surface. The in-house test-rig of TENGs resulted in an output open-circuit voltage of 120 V and a shortcircuit current of 23.7 μA. Further, the maximum power density is 7.125 W/m 2 at an external load resistance of 30 MΩ. These results suggest that La 2 O 3 is a suitable contender in various self-powered devices.
This paper presents a new type of one-dimensional photonic crystal (PC) waveguide sensor and a technique for prediction of transient strain response accurately. The PC waveguide is integrated on a silicon substrate. We investigate the effect of non-uniform strain localization on the optical signal and use that information to capture the transient strain. Wavelength shift due to distributed strain field is modeled by incorporating the mechanically deformed geometry and photo-acoustic coupling through Pockels effect in a finite element formulation. We demonstrate the advantages of using our proposed method, where multiple spectral peak shift is used instead of single peak shift in order to improve sensing output accuracy and also to estimate the sensor parameter regressively, where the signal's bandwidth is limited. The maximum sensitivity of the waveguide sensor in terms of wavelength shift is estimated to be 0.36 pm/μstrain in single-peak-based sensing, whereas the proposed adaptive multispectral estimation scheme shows an enhanced sensitivity of 4.029 pm/μstrain.
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