Design and Optimization of Ultrasonic Links With Phased Arrays for Wireless Power Transmission to Biomedical Implants

Zeinab Kashani, Sheikh Jawad Ilham, Mehdi Kiani

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Ultrasound (US) is an attractive modality for wireless power transfer (WPT) to biomedical implants with millimeter (mm) dimensions. To compensate for misalignments in WPT to a mm-sized implant (or powering a network of mm-sized implants), a US transducer array should electronically be driven in a beamforming fashion (known as US phased array) to steer focused US beams at different locations. This paper presents the theory and design methodology of US WPT links with phased arrays and mm-sized receivers (Rx). For given constraints imposed by the application and fabrication, such as load (RL) and focal distance (F), the optimal geometries of a US phased array and Rx transducer, as well as the optimal operation frequency (fc) are found through an iterative design procedure to maximize the power transfer efficiency (PTE). An optimal figure of merit (FoM) related to PTE is proposed to simplify the US array design. A design example of a US link is presented and optimized for WPT to a mm-sized Rx with a linear array. In measurements, the fabricated 16-element array (10.9×9×1.7 mm3) driven by 100 V pulses at fc of 1.1 MHz with optimal delays for focusing at F = 20 mm generated a US beam with a pressure output of 0.8 MPa. The link could deliver up to 6 mW to a ∼ 1 mm3 Rx with a PTE of 0.14% (RL = 850 Ω). The beam steering capability of the array at -45o to 45o angles was also characterized.

Original languageEnglish (US)
Pages (from-to)64-78
Number of pages15
JournalIEEE transactions on biomedical circuits and systems
Volume16
Issue number1
DOIs
StatePublished - Feb 1 2022

All Science Journal Classification (ASJC) codes

  • Biomedical Engineering
  • Electrical and Electronic Engineering

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