| Popis: |
Determining the exact location of people and objects is a big benefit in times of IoT. It can achieve a tailored surrounding for humans for example by controlling lights or air conditioning systems when needed thus saving energy. It can also help with a smoother navigation for example by pointing to available spaces for parking cars or storing goods. In order to conclude an accurate location, large networks of connected sensors are required. These sensors can either be attached to the tracked target or tied to the monitored location. Either way, powering this growing number of sensors poses a challenge. Energy harvesters utilizing the transverse piezoelectric property of PVDF are proposed in order to power such sensors, eliminating the hassle of complex wiring or inconvenient battery replacements. A device that harvests mechanical energy from steps or movement using a multilayered wrap of PVDF-foils has been designed and fabricated. Depending on the application, this energy harvester can be installed in the ground of monitored locations or within the surface of tracked objects. Experimental characterizations of the energy output based on the number of windings and the required force have been conducted. A PVDF-wrap with three windings delivers 3.7 mJ when a force of 640 N, more or less the average human step force, is applied. Wireless sensors nodes, usually requiring less than 1 mJ to detect and transmit an event, can therefore be powered regardless of their location and without the need for inconvenient battery replacements. |
