Unobstructive and safe-to-wear watt-level wireless charger
Source abstract
Abstract
A wearable microgrid that centralizes and distributes harvested energy across different body regions can optimize power utilization and reduce overall battery weight. This setup underscores the importance of developing cable-free wireless power transfer (WPT) systems for mobile and portable devices to eliminate the risks posed by wired connections, especially in dynamic and hazardous environments. We introduce a thin, stretchable, and safe hand band capable of watt-level wireless charging through the widely adopted Qi protocol operating at 130 kHz. The implementation of non-adhesive fabric encapsulation serves to protect the 50-μm-thin spiral copper antenna from mechanical strain, ensuring an overall hand band stretchability of 50%. We also create a stretchable “Ferrofabric”, characterized by a magnetic permeability of 11.3 and a tensile modulus of 75.3 kPa, that provides magnetic shielding for the antenna without compromising wearability. The “Ferrofabric” improves the coil inductance but induces core loss in AC application. By fully understanding and managing loss mechanisms such as the skin effect, proximity effect, core loss, and joule heating, we achieve a wireless charging efficiency of 71% and power delivery of 3.81 W in the kHz frequency range. Our WPT hand band is unobstructive to hand motion and can charge a handheld smartphone as fast as a desktop charger or power a battery-free chest-laminated e-tattoo sensor, with well-managed thermal and electromagnetic safety. Through a holistic electromagnetic, structural, and thermal design, our device culminates in a safe, rugged, and versatile solution for wearable WPT systems.
Source: openalex_inverted_index · Quality: baseline
Research context
OpenAlex topics: Advanced Sensor and Energy Harvesting Materials · Wireless Power Transfer Systems · Energy Harvesting in Wireless Networks
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (75)
Show source-provided references
1. Pu, X., Hu, W. & Wang, Z. L. Toward wearable self‐charging power systems: the integration of energy‐harvesting and storage devices. Small 14, 1702817 (2018).10.1002/smll.201702817 ↗
2. Ray, T. R. et al. Bio-integrated wearable systems: a comprehensive review. Chem. Rev. 119, 5461–5533 (2019).10.1021/acs.chemrev.8b00573 ↗
3. Luo, Y. et al. Technology roadmap for flexible sensors. ACS Nano 17, 5211–5295 (2023).10.1021/acsnano.2c12606 ↗
4. Li, H. et al. E-tattoos: toward functional but imperceptible interfacing with human skin. Chem. Rev. 124, 3220–3283 (2024).10.1021/acs.chemrev.3c00626 ↗
5. Yin, L., Kim, K. N., Trifonov, A., Podhajny, T. & Wang, J. Designing wearable microgrids: towards autonomous sustainable on-body energy management. Energy Environ. Sci. 15, 82–101 (2022).10.1039/D1EE03113A ↗
6. Yin, J. et al. Smart textiles for self-powered biomonitoring. Med-X 1, 3 (2023).10.1007/s44258-023-00001-3 ↗
7. Yin, L. et al. A self-sustainable wearable multi-modular E-textile bioenergy microgrid system. Nat. Commun. 12, 1542 (2021).10.1038/s41467-021-21701-7 ↗
8. Niu, S. et al. A wireless body area sensor network based on stretchable passive tags. Nat. Electron. 2, 361–368 (2019).10.1038/s41928-019-0286-2 ↗
9. Niu, S., Wang, X., Yi, F., Zhou, Y. S. & Wang, Z. L. A universal self-charging system driven by random biomechanical energy for sustainable operation of mobile electronics. Nat. Commun. 6, 8975 (2015).10.1038/ncomms9975 ↗
10. Tian, X. et al. Wireless body sensor networks based on metamaterial textiles. Nat. Electron. 2, 243–251 (2019).10.1038/s41928-019-0257-7 ↗
11. Hajiaghajani, A. et al. Textile-integrated metamaterials for near-field multibody area networks. Nat. Electron. 4, 808–817 (2021).10.1038/s41928-021-00663-0 ↗
12. Chaari, M. Z., Al-Rahimi, R. & Aghzout, O. High power wireless power transfer for the future of the battle field challenges. Secur. Def. Q. 4, 9–26 (2022).
13. Magnuson, S. Power-hungry devices challenge Army researchers. Natl. Def. 101, 37–38 (2017).
14. Mardonova, M. & Choi, Y. Review of wearable device technology and its applications to the mining industry. Energies 11, 547 (2018).10.3390/en11030547 ↗
15. Hofer, I. & Cannesson, M. Is wireless the future of monitoring? Anesth. Analg. 122, 305–306 (2016).10.1213/ANE.0000000000001058 ↗
16. Wahlman, A., Clavin, C. T., Keller, R. A., Georgi, D. M. & Ayers, J. R. Assessment of the Challenges Associated with Individual Battlefield Power: Addressing the Power Budget Burdens of the Warfighter and Squad (Institute for Defense Analyses, 2022).
17. Masrur, M. A. & Cox, M. A unique military application of wireless power transfer: wireless charging through a vehicle seat with simplified design considerations. IEEE Ind. Electron. Mag. 13, 19–30 (2019).10.1109/MIE.2019.2937469 ↗
18. Yao, W., Ng, K. F., Xiao, H., Wang, K. & Mao, Y. In 2022 IEEE 9th International Conference on Power Electronics Systems and Applications (PESA) (IEEE, 2022).
19. Kim, C. Y. et al. Soft subdermal implant capable of wireless battery charging and programmable controls for applications in optogenetics. Nat. Commun. 12, 535 (2021).10.1038/s41467-020-20803-y ↗
20. Yu, X. et al. Skin-integrated wireless haptic interfaces for virtual and augmented reality. Nature 575, 473–479 (2019).10.1038/s41586-019-1687-0 ↗
21. Li, J., Dong, Y., Park, J. H. & Yoo, J. Body-coupled power transmission and energy harvesting. Nat. Electron. 4, 530–538 (2021).10.1038/s41928-021-00592-y ↗
22. Kim, D.-H. et al. Epidermal electronics. Science 333, 838–843 (2011).10.1126/science.1206157 ↗
23. Joo, H. et al. Soft implantable drug delivery device integrated wirelessly with wearable devices to treat fatal seizures. Sci. Adv. 7, eabd4639 (2021).10.1126/sciadv.abd4639 ↗
24. Li, C. et al. Flexible perovskite solar cell-driven photo-rechargeable lithium-ion capacitor for self-powered wearable strain sensors. Nano Energy 60, 247–256 (2019).10.1016/j.nanoen.2019.03.061 ↗
25. Liu, M., Qian, F., Mi, J. & Zuo, L. Biomechanical energy harvesting for wearable and mobile devices: state-of-the-art and future directions. Appl. Energy 321, 119379 (2022).10.1016/j.apenergy.2022.119379 ↗
26. Amjadi, M., Yoon, Y. J. & Park, I. Ultra-stretchable and skin-mountable strain sensors using carbon nanotubes–Ecoflex nanocomposites. Nanotechnology 26, 375501 (2015).10.1088/0957-4484/26/37/375501 ↗
27. Seo, Y.-S. et al. Wireless power transfer for a miniature gastrostimulator. In 2012 42nd European Microwave Conference (IEEE, 2012).10.23919/EuMC.2012.6459301 ↗
28. Alrashdan, F. T. et al. Wearable wireless power systems for ‘ME-BIT’ magnetoelectric-powered bio implants. J. Neural Eng. 18, 045011 (2021).10.1088/1741-2552/ac1178 ↗
29. Kod, M. et al. An approach to improve the misalignment and wireless power transfer into biomedical implants using meandered wearable loop antenna. Wirel. Power Transf. 2021, 1–12 (2021).
30. Yu, Z. et al. MagNI: a magnetoelectrically powered and controlled wireless neurostimulating implant. IEEE Trans. Biomed. Circuits Syst. 14, 1241–1252 (2020).10.1109/TBCAS.2020.3037862 ↗
31. Lin, R. et al. Digitally-embroidered liquid metal electronic textiles for wearable wireless systems. Nat. Commun. 13, 2190 (2022).10.1038/s41467-022-29859-4 ↗
32. Zhang, Y. et al. High precision epidermal radio frequency antenna via nanofiber network for wireless stretchable multifunction electronics. Nat. Commun. 11, 1–10 (2020).10.1038/s41467-019-13993-7 ↗
33. Barron, E. J. III, Peterson, R. S., Lazarus, N. & Bartlett, M. D. Mechanically cloaked multiphase magnetic elastomer soft composites for wearable wireless power transfer. ACS Appl. Mater. Interfaces 12, 50909–50917 (2020).10.1021/acsami.0c15909 ↗
34. Jeong, H. et al. Modular and reconfigurable wireless e‐tattoos for personalized sensing. Adv. Mater. Technol. 4, 1900117 (2019).10.1002/admt.201900117 ↗
35. Teng, L., Zhu, L., Handschuh-Wang, S. & Zhou, X. Robust, multiscale liquid-metal patterning enabled by a sacrificial sealing layer for flexible and wearable wireless powering. J. Mater. Chem. C 7, 15243–15251 (2019).10.1039/C9TC04876F ↗
36. Xu, S. et al. Stretchable batteries with self-similar serpentine interconnects and integrated wireless recharging systems. Nat. Commun. 4, 1543 (2013).10.1038/ncomms2553 ↗
37. Dautta, M. et al. Wireless Qi-powered, multinodal and multisensory body area network for mobile health. IEEE Internet Things J. 8, 7600–7609 (2021).10.1109/JIOT.2020.3040713 ↗
38. Liu, Y. et al. Epidermal mechano-acoustic sensing electronics for cardiovascular diagnostics and human-machine interfaces. Sci. Adv. 2, e1601185 (2016).10.1126/sciadv.1601185 ↗
39. Sun, Y., Choi, W. M., Jiang, H., Huang, Y. Y. & Rogers, J. A. Controlled buckling of semiconductor nanoribbons for stretchable electronics. Nat. Nanotechnol. 1, 201–207 (2006).10.1038/nnano.2006.131 ↗
40. Yang, S. et al. “Cut‐and‐paste” manufacture of multiparametric epidermal sensor systems. Adv. Mater. 27, 6423–6430 (2015).10.1002/adma.201502386 ↗
41. Ye, J., Xing, Z.-R., Gao, J.-Y. & Liu, J. Liquid metal coil. Mater. Today Commun. 32, 104120 (2022).10.1016/j.mtcomm.2022.104120 ↗
42. Lin, R. et al. Wireless battery-free body sensor networks using near-field-enabled clothing. Nat. Commun. 11, 444 (2020).10.1038/s41467-020-14311-2 ↗
43. Sun, D. et al. Investigating flexible textile-based coils for wireless charging wearable electronics. J. Ind. Text. 50, 333–345 (2020).10.1177/1528083719831086 ↗
44. Barreto, J., Kaddour, A.-S., An, H. S., Sheperd, R. & Georgakopoulos, S. V. Optimal embroidered wearable WPT systems with liquid metal nanoparticles. In 2021 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting (APS/URSI) (IEEE, 2021).10.1109/APS/URSI47566.2021.9704539 ↗
45. Rahman, M. S., Huddy, J. E., Hamlin, A. B. & Scheideler, W. J. Broadband mechanoresponsive liquid metal sensors. npj Flex. Electron 6, 71 (2022).10.1038/s41528-022-00206-3 ↗
46. Lazarus, N. & Bedair, S. Improved power transfer to wearable systems through stretchable magnetic composites. Appl. Phys. A 122, 1–7 (2016).10.1007/s00339-016-0067-y ↗
47. Lu, X., Wang, P., Niyato, D., Kim, D. I. & Han, Z. Wireless charging technologies: fundamentals, standards, and network applications. IEEE Commun. Surv. Tutor. 18, 1413–1452 (2016).10.1109/COMST.2015.2499783 ↗
48. Meile, L., Ulrich, A. & Magno, M. Wireless power transmission powering miniaturized low power IoT devices: a revie. In 2019 IEEE 8th International Workshop on Advances in Sensors and Interfaces (IWASI) (IEEE, 2019).10.1109/IWASI.2019.8791433 ↗
49. Mohanarangam, K., Palagani, Y. & Choi, J. Evaluation of specific absorption rate in three-layered tissue model at 13.56 MHz and 40.68 MHz for inductively powered biomedical implants. Appl. Sci. 9, 1125 (2019).10.3390/app9061125 ↗
50. Samsung Electronics. SAR Information. https://www.samsung.com/sar/sarMain?site_cd=&prd_mdl_name=SM-S928U&selNatCd=US&languageCode=EN (2024)
51. Tian, X. et al. Implant-to-implant wireless networking with metamaterial textiles. Nat. Commun. 14, 4335 (2023).10.1038/s41467-023-39850-2 ↗
52. Siman-Tov, E., Tseng, V. F.-G., Bedair, S. S. & Lazarus, N. Increasing the range of wireless power transmission to stretchable electronics. IEEE Trans. Microw. Theory Tech. 66, 5021–5030 (2018).
53. Gao, W., Wang, L., Wang, X. & Liu, H. Magnetic driving flowerlike soft platform: Biomimetic fabrication and external regulation. ACS Appl. Mater. Interfaces 8, 14182–14189 (2016).10.1021/acsami.6b03218 ↗
54. Lazarus, N., Meyer, C. D., Bedair, S. S., Slipher, G. A. & Kierzewski, I. M. Magnetic elastomers for stretchable inductors. ACS Appl. Mater. Interfaces 7, 10080–10084 (2015).10.1021/acsami.5b02189 ↗
55. Hu, X., Fu, Y., Wu, T. & Qu, S. Study of non-uniform axial magnetic field induced deformation of a soft cylindrical magneto-active actuator. Soft Matter 17, 7498–7505 (2021).10.1039/D1SM00757B ↗
56. Diguet, G., Froemel, J., Muroyama, M. & Ohtaka, K. Tactile sensing using magnetic foam. Polymers 14, 834 (2022).10.3390/polym14040834 ↗
57. Li, J. et al. Design and fabrication of microfluidic mixer from carbonyl iron–PDMS composite membrane. Microfluid. Nanofluidics 10, 919–925 (2011).10.1007/s10404-010-0712-2 ↗
58. Denver, H., Heiman, T., Martin, E., Gupta, A. & Borca-Tasciuc, D.-A. Fabrication of polydimethylsiloxane composites with nickel nanoparticle and nanowire fillers and study of their mechanical and magnetic properties. J. Appl. Phys. 106, 064909 (2009).10.1063/1.3224966 ↗
59. Pirmoradi, F. N., Cheng, L. & Chiao, M. A magnetic poly (dimethylesiloxane) composite membrane incorporated with uniformly dispersed, coated iron oxide nanoparticles. J. Micromech. Microeng. 20, 015032 (2009).10.1088/0960-1317/20/1/015032 ↗
60. Lazarus, N., Bedair, S. S. & Smith, G. L. Creating 3D printed magnetic devices with ferrofluids and liquid metals. Addit. Manuf. 26, 15–21 (2019).
61. Lazarus, N. & Meyer, C. Stretchable inductor with liquid magnetic core. Mater. Res. Express 3, 036103 (2016).10.1088/2053-1591/3/3/036103 ↗
62. Liu, J., Yu, M.-Y., Yu, Z.-Z. & Nicolosi, V. Design and advanced manufacturing of electromagnetic interference shielding materials. Mater. Today 66, 245–272 (2023).10.1016/j.mattod.2023.03.022 ↗
63. Maaß, M., Griessner, A., Steixner, V. & Zierhofer, C. Reduction of eddy current losses in inductive transmission systems with ferrite sheets. BioMed. Eng. OnLine 16, 1–18 (2017).10.1186/s12938-016-0297-4 ↗
64. Bhattacharya, S. et al. A chest‐conformable, wireless electro‐mechanical e‐tattoo for measuring multiple cardiac time intervals. Adv. Electron. Mater. 9, 2201284 (2023).10.1002/aelm.202201284 ↗
65. Huang, W. et al. Monolithic mtesla-level magnetic induction by self-rolled-up membrane technology. Sci. Adv. 6, eaay4508 (2020).10.1126/sciadv.aay4508 ↗
66. Bury, E., Thiagarajan, S., Lazarus, N. & Koh, A. Ferrofluid high internal phase emulsion polymer foams for soft, magnetic materials. J. Magn. Magn. Mater. 563, 169921 (2022).10.1016/j.jmmm.2022.169921 ↗
67. Shen, Q. et al. Liquid metal-based soft, hermetic, and wireless-communicable seals for stretchable systems. Science 379, 488–493 (2023).10.1126/science.ade7341 ↗
68. Lee, E. S. & Choi, B. G. Calculation methodologies of complex permeability for various magnetic materials. Electronics 10, 2167 (2021).10.3390/electronics10172167 ↗
69. Taalla, R. V., Arefin, M. S., Kaynak, A. & Kouzani, A. Z. A review on miniaturized ultrasonic wireless power transfer to implantable medical devices. IEEE Access 7, 2092–2106 (2019).10.1109/ACCESS.2018.2886780 ↗
70. Jow, U.-M. & Ghovanloo, M. Modeling and optimization of printed spiral coils in air, saline, and muscle tissue environments. IEEE Trans. Biomed. Circuits Syst. 3, 339–347 (2009).10.1109/TBCAS.2009.2025366 ↗
71. Mohammad, M., Choi, S. & Elbuluk, M. E. Loss minimization design of ferrite core in a DD-coil-based high-power wireless charging system for electrical vehicle application. IEEE Trans. Transp. Electrific. 5, 957–967 (2019).10.1109/TTE.2019.2940878 ↗
72. Wang, H. et al. Folding and bending planar coils for highly precise soft angle sensing. Adv. Mater. Technol. 5, 2000659 (2020).10.1002/admt.202000659 ↗
73. Stier, A. et al. Stretchable tattoo-like heater with on-site temperature feedback control. Micromachines 9, 170 (2018).10.3390/mi9040170 ↗
74. Ryu, H. et al. Materials and device designs for wireless monitoring of temperature and thermal transport properties of wound beds during healing. Adv. Healthc. Mater. 13, 2302797 (2024).10.1002/adhm.202302797 ↗
75. Rhee, J. et al. Wireless torque and power transfer using multiple coils with LCC-S topology for implantable medical drug pump. Sensors 21, 8150 (2021).10.3390/s21238150 ↗