Harvesting vibrational energy using material work functions

Aapo Varpula (Corresponding Author), Sampo Laakso, Tahvo Havia, Jukka Kyynäräinen, Mika Prunnila (Corresponding Author)

    Research output: Contribution to journalArticleScientificpeer-review

    30 Citations (Scopus)


    Vibration energy harvesters scavenge energy from mechanical vibrations to energise low power electronic devices. In this work, we report on vibration energy harvesting scheme based on the charging phenomenon occurring naturally between two bodies with different work functions. Such work function energy harvester (WFEH) is similar to electrostatic energy harvester with the fundamental distinction that neither external power supplies nor electrets are needed. A theoretical model and description of different operation modes of WFEHs are presented. The WFEH concept is tested with macroscopic experiments, which agree well with the model. The feasibility of miniaturizing WFEHs is shown by simulating a realistic MEMS device. We show that the WFEH can be operated using either a charge shuttle or, with switches, as a charge pump that pushes charge and energy into an energy storage element. It is also shown that such an operation mode is highly desirable for applications. The WFEH is shown to give equal or better output power in comparison to traditional electrostatic harvesters. Our findings indicate that WFEH has great potential in energy harvesting applications.
    Original languageEnglish
    Article number6799
    JournalScientific Reports
    Publication statusPublished - 2014
    MoE publication typeA1 Journal article-refereed


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