A Self‐Powered Flow Velocity Sensing System Based on Hybrid Piezo‐Triboelectric Nanogenerator

Abstract

Monitoring the flow velocity of an urban ventilation system has great significance for air circulation and air quality. In this study, a self‐powered flow velocity sensor based on hybrid piezo‐triboelectric nanogenerator (P‐TENG) is proposed. The flow velocity is detected by a triboelectric nanogenerator (TENG) working in freestanding triboelectric‐layer mode. A polyvinylidene difluoride (PVDF) fixed on the galloping beam converts the kinetic energy of the moving air into electricity. Both the TENG and PVDF are driven by the galloping vibration of a bluff body arisen from the air flow of ventilation. The structure of the P‐TENG is provided and a prototype is fabricated. The experiments indicate that the PVDF can generate 2.4 µW of energy across an external resistance of 60 MΩ. Flow velocity ranging from 4 to 10 m s−1 can be well detected by the proposed nanogenerator. Moreover, the P‐TENG is applicable to a critical environment with humidity up to 75%. Demonstration is carried out on a wind tunnel, illustrating good reliability as the frequency remains stable for the whole duration. Compared with the commercial anemometer, the error rate is under 1% after calibration. The proposed P‐TENG promises in low cost, self‐powered flow velocity monitoring in urban ventilation systems.

Recent Progress in Flow Energy Harvesting and Sensing Based on Triboelectric Nanogenerators

“…As shown in Figure 10e, in order to convert the flow velocity into vibratory oscillations, a square obstacle‐beam structure is designed, where the square obstacle is a beam made of spring steel fixed on the base. [ 157 ] The TENG consists of a moving FEP film and fixed interconnect electrodes at the bottom of the obstacle. The vibratory oscillations of the obstacles drive the FEP film across the interconnecting electrodes based on triboelectrification, generating an electrical signal.…”

“…TENG-based flow rate sensors can be employed to measure the flow rate of fluids in pipelines, channels, or other fluidic systems. [153][154][155][156][157][158][159][160][161][162] Various TENG designs, including flappingbased, cylinder-based, and turbine-based TENGs, can be used to capture the mechanical energy from fluid flows and convert it into electrical signals. The electrical output of the TENG can be correlated with the flow rate, providing accurate and real-time measurements.…”

Advances in Triboelectric Flow Sensor

“…[3,121,[126][127][128] For materials, the output performance can be further optimized by surface treatment. [129][130][131] Based on these advantages, it has been widely used in displacement sensors, [132][133][134][135][136] pressure sensors, [137][138][139][140] vibration sensors, [120,[141][142][143][144][145] velocity sensors [146][147][148] and flow sensors. [149][150][151][152] Compared with the traditional power-supplied sensors, one of the major advantages of these triboelectric sensors is that they do not need additional power supply or chemical battery power supply, [153] because they rely on the electrical output generated by the mechanical trigger directly as the detection signal, which provides an effective solution to realize the intelligent and wireless development of flow monitoring.…”