Head-compliant microstrip split ring resonator for non-invasive healing monitoring after craniosynostosis-based surgery

Mauricio David Perez; Seung Hee Jeong; Sujith Raman; Daniel Nowinski; Zhigang Wu; Syaiful M S Redzwan; Jacob Velander; Zhiwei Peng; Klas Hjort; Robin Augustine

doi:10.1049/htl.2018.5083

Head-compliant microstrip split ring resonator for non-invasive healing monitoring after craniosynostosis-based surgery

Healthc Technol Lett. 2020 Feb 17;7(1):29-34. doi: 10.1049/htl.2018.5083. eCollection 2020 Feb.

Authors

Affiliations

¹ Department of Engineering Sciences, The Angstrom Laboratory, Uppsala University, 751 21 Uppsala, Sweden.
² Department of Electronics and Instrumentation, Bharathiar University, Coimbatore, India.
³ Department of Surgical Sciences, Uppsala University Hospital, 751 85 Uppsala, Sweden.
⁴ State Key Laboratory of Digital Manufacturing and Equipment Technology, School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074, People's Republic of China.
⁵ School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan 410083, People's Republic of China.

Abstract

A soft and highly directive, proximity-coupled split-ring resonator fabricated with a liquid alloy, copper and polydimethylsiloxane (PDMS) is presented. The same was designed for sensing osteogenesis of calvarial bone. As dielectric properties of bone grafts in ossifying calvarial defects should change during the osteogenesis process, devices like this could monitor the gradual transformation of the defect into bone by differentiating changes in the dielectric properties as shifts in the resonance frequency. Computational Software Technology (CST) Microwave Studio®-based simulation results on computational head models were in good agreement with laboratory results on head phantom models, which also included the comparison with an in-vivo measurement on the human head. A discussion based on an inductive reasoning regarding dynamics' considerations is provided as well. Since the skin elasticity of newborn children is high, stretching and crumpling could be significant. In addition, due to typical head curvatures in newborn children, bending should not be a significant issue, and can provide higher energy focus in the defect area and improve conformability. The present concept could support the development of soft, cheap and portable follow-up monitoring systems to use in outpatient hospital and home care settings for post-operative monitoring of bone healing after reconstructive surgical procedures.

Keywords: bending; biomechanics; biomedical equipment; bone; bone grafts; bone healing; calvarial bone osteogenesis; calvarial defects; computational head models; computational software technology microwave studio-based simulation; copper; craniosynostosis-based surgery; defect area; dielectric properties; elasticity; head curvatures; head phantom models; head-compliant microstrip split ring resonator; highly directive proximity-coupled split-ring resonator; human head; liquid alloy; liquid alloys; microstrip resonators; microwave resonators; monitoring systems; newborn children; noninvasive healing monitoring; osteogenesis process; paediatrics; patient monitoring; phantoms; polydimethylsiloxane; post-operative monitoring; reconstructive surgical procedures; resonance frequency; skin; skin elasticity; soft proximity-coupled split-ring resonator; split ring resonators; surgery.