Rotational piezoelectric energy harvester for wearable devices

Electronic devices are mostly powered externally via batteries. The dependency on the recharging process limits the usage of these devices to work in a specified period of time. This research work highlights the capability of a piezoelectric energy harvester to generate sufficient electricity to power up electronic devices by using low frequency vibrations alone, without relying on external power supplies. In general human motions consists of low frequency vibrations, therefore the capability to power up electronic devices using low frequency vibrations will also eventually become useful to power up wearable devices. Simulations were conducted using COMSOL Multiphysics® to identify the dimensions of a piezoelectric beam which will produce the optimum level of voltage output. A specially fabricated rotational piezoelectric energy harvester prototype that consists of a 40 mm piezoelectric bimorph beam that rotates with the aid of a rotor and aluminum proof-mass was developed together with a corresponding Arduino Uno based data logger. With a given input frequency of 18 Hz, the maximum voltage output that could be generated was recorded at 0.024 V. This research highlights the optimistic possibility that clean energy could be generated and utilized in powering various applications without depending on external power supplies

Piezoelectric based broadband nonlinear vibration energy harvester using multiple magnets

The advancement of technology has made low-powered devices such as wireless sensor network powered using small battery become possible. However, this type of battery has limited lifespan and needed to be changed frequently which is not convenient when placed in remote area or harsh environment. Therefore, devices that can harvest energy from their surrounding are preferred. One of the famous method is by using piezoelectric transducer to scavenge ambient vibration energy. However, the piezoelectric harvester (PEH) usually has small bandwidth that it can operate. This paper proposed a PEH in the form of cantilever beam with a tip mass along with multiple fixed magnets in certain configuration. The proposed design uses external force by magnet to alter its stiffness and then due the nonlinearity effect introduced by magnets, the operating bandwidth of the PEH is increased. With proper configuration, the proposed design has improved bandwidth compared to PEH without any magnet. It is also found that power output of proposed PEH is relatively higher than conventional PEH which is about 1314 µW where this value is enough to power up low-powered device. In addition, the power per frequency of proposed PEH is 81.59 µW/Hz, which is about 64 percent higher than the PEH without any magnet