{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,25]],"date-time":"2026-07-25T05:34:02Z","timestamp":1784957642771,"version":"3.55.0"},"reference-count":52,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2024,8,12]],"date-time":"2024-08-12T00:00:00Z","timestamp":1723420800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Battery power is crucial for wearable devices as it ensures continuous operation, which is critical for real-time health monitoring and emergency alerts. One solution for long-lasting monitoring is energy harvesting systems. Ensuring a consistent energy supply from variable sources for reliable device performance is a major challenge. Additionally, integrating energy harvesting components without compromising the wearability, comfort, and esthetic design of healthcare devices presents a significant bottleneck. Here, we show that with a meticulous design using small and highly efficient photovoltaic (PV) panels, compact thermoelectric (TEG) modules, and two ultra-low-power BQ25504 DC-DC boost converters, the battery life can increase from 9.31 h to over 18 h. The parallel connection of boost converters at two points of the output allows both energy sources to individually achieve maximum power point tracking (MPPT) during battery charging. We found that under specific conditions such as facing the sun for more than two hours, the device became self-powered. Our results demonstrate the long-term and stable performance of the sensor node with an efficiency of 96%. Given the high-power density of solar cells outdoors, a combination of PV and TEG energy can harvest energy quickly and sufficiently from sunlight and body heat. The small form factor of the harvesting system and the environmental conditions of particular occupations such as the oil and gas industry make it suitable for health monitoring wearables worn on the head, face, or wrist region, targeting outdoor workers.<\/jats:p>","DOI":"10.3390\/s24165219","type":"journal-article","created":{"date-parts":[[2024,8,12]],"date-time":"2024-08-12T11:23:46Z","timestamp":1723461826000},"page":"5219","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Designing a Hybrid Energy-Efficient Harvesting System for Head- or Wrist-Worn Healthcare Wearable Devices"],"prefix":"10.3390","volume":"24","author":[{"given":"Zahra","family":"Tohidinejad","sequence":"first","affiliation":[{"name":"Department of Electrical Engineering, Ilam University, Ilam 69315-516, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2873-6469","authenticated-orcid":false,"given":"Saeed","family":"Danyali","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, Ilam University, Ilam 69315-516, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Majid","family":"Valizadeh","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, Ilam University, Ilam 69315-516, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5192-2537","authenticated-orcid":false,"given":"Ralf","family":"Seepold","sequence":"additional","affiliation":[{"name":"Ubiquitous Computing Laboratory, HTWG Konstanz\u2014University of Applied Sciences, 78462 Konstanz, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nima","family":"TaheriNejad","sequence":"additional","affiliation":[{"name":"Institute of Computer Engineering, Heidelberg University, 69120 Heidelberg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8966-0176","authenticated-orcid":false,"given":"Mostafa","family":"Haghi","sequence":"additional","affiliation":[{"name":"Institute of Computer Engineering, Heidelberg University, 69120 Heidelberg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,8,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Hasasneh, A., Hijazi, H., Talib, M.A., Afadar, Y., Nassif, A.B., and Nasir, Q. 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