Continuous monitoring of deep-tissue haemodynamics with stretchable ultrasonic phased arrays

Wang, Chonghe; Qi, Baiyan; Lin, Muyang; Zhang, Zhuorui; Makihata, Mitsutoshi; Liu, Boyu; Zhou, Sai; Huang, Yi-Hsi; Hu, Hongjie; Gu, Yue; Chen, Yimu; Lei, Yusheng; Lee, Taeyoon; Chien, Shu; Jang, Kyung‐In; Kistler, Erik B.; Xu, Sheng

doi:10.1038/s41551-021-00763-4

Cited by 139 publications

(111 citation statements)

References 66 publications

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“…Most ultrasound arrays require gel for acoustic coupling, but this is not ideal for long-term applications. A flexible or stretchable array could conform to the skin without the need for gel, as has recently been demonstrated [32]. Due to the power-limited environment of a wearable device and the desire to dissipate the minimum amount of acoustic energy in tissue while powering chronic implants, beamforming efficiency should be maximized.…”

Section: Discussionmentioning

confidence: 99%

Phased array beamforming methods for powering biomedical ultrasonic implants

Benedict¹,

Ghanbari²,

Muller³

2022

Preprint

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Millimeter-scale implants using ultrasound for power and communication have been proposed for a range of deep-tissue applications, including neural recording and stimulation. However, published implementations have shown high sensitivity to misalignment with the external ultrasound transducer. Ultrasonic beamforming using a phased array to these implants can improve tolerance to misalignment, reduce implant volume, and allow multiple implants to be operated simultaneously in different locations. This paper details the design of a custom planar phased array ultrasound system, which is capable of steering and focusing ultrasound power within a 3D volume. Analysis and simulation is performed to determine the choice of array element pitch, with special attention given to maximizing the power available at the implant while meeting FDA limits for diagnostic ultrasound. Time reversal is proposed as a computationally simple approach to beamforming that is robust despite scattering and inhomogeneity of the acoustic medium. This technique is demonstrated both in active drive and pulse-echo modes, and it is experimentally compared with other beamforming techniques by measuring energy transfer efficiency at varying depths and angles. Simultaneous power delivery to multiple implants is also demonstrated.

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Section: Discussionmentioning

confidence: 99%

Phased array beamforming methods for powering biomedical ultrasonic implants

Benedict¹,

Ghanbari²,

Muller³

2022

Preprint

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“…Other mechanisms of flexible health monitoring in rehabilitation, like optoelectronic [263,264] and ultrasound [265,266] devices, can also be applied to heartbeat, pulse oximetry, blood pressure, and other on-body measurements. As an example, organic flexible light emitting diodes (LEDs) and photodiodes are driving the application of photoplethysmogram (PPG) in the wearable sector.…”

Section: Other Sensing Techniquesmentioning

confidence: 99%

Flexible Electronics and Devices as Human–Machine Interfaces for Medical Robotics

2022

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Medical robots are invaluable players in non-pharmaceutical treatment of disabilities. Particularly, using prosthetic and rehabilitation devices with human-machine interfaces can greatly improve the quality of life for impaired patients. In recent years, flexible electronic interfaces and soft robotics have attracted tremendous attention in this field due to their high biocompatibility, functionality, conformability, and low-cost. Flexible human-machine interfaces on soft robotics would make a promising alternative to conventional rigid devices, which could potentially revolutionize the paradigm and future direction of medical robotics in terms of rehabilitation feedback and user experience. In this review, the fundamental components of the materials, structures, and mechanisms in flexible humanmachine interfaces are summarized by recent and renown applications in five primary areas: physical and chemical sensing, physiological recording, information processing and communication, soft robotic actuation, and feedback stimulation. This review further concludes by discussing the outlook and current challenges of these technologies as a human-machine interface in medical robotics.

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“…The development of MEMS technology and flexible electronic technology enables a possible solution to these problems. Some miniaturized ultrasound probes [ 25 , 26 , 27 ] and stretchable ultrasound wearable devices have been developed for blood pressure and blood flow velocity monitoring [ 24 , 28 , 29 ]. However, there is no research on flexible ultrasound devices for local PWV monitoring.…”

Section: Introductionmentioning

confidence: 99%

A Flexible Ultrasound Array for Local Pulse Wave Velocity Monitoring

Wang

Pan

et al. 2022

Biosensors

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Pulse wave velocity (PWV) measured at a specific artery location is called local PWV, which provides the elastic characteristics of arteries and indicates the degree of arterial stiffness. However, the large and cumbersome ultrasound probes require an appropriate sensor position and pressure maintenance, introducing usability constraints. In this paper, we developed a light (0.5 g) and thin (400 μm) flexible ultrasound array by encapsulating 1–3 composite piezoelectric transducers with a silicone elastomer. It can capture the distension waveforms of four arterial positions with a spacing of 10 mm and calculate the local PWV by multi-point fitting. This is illustrated by in vivo experiments, where the local PWV value of five normal subjects ranged from 3.07 to 4.82 m/s, in agreement with earlier studies. The beat-to-beat coefficient of variation (CV) is 12.0% ± 3.5%, showing high reliability. High reproducibility is shown by the results of two groups of independent measurements of three subjects (the error between the mean values is less than 0.3 m/s). These properties of the developed flexible ultrasound array enable the bandage-like application of local PWV monitoring to skin surfaces.

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Continuous monitoring of deep-tissue haemodynamics with stretchable ultrasonic phased arrays

Cited by 139 publications

References 66 publications

Phased array beamforming methods for powering biomedical ultrasonic implants

Phased array beamforming methods for powering biomedical ultrasonic implants

Flexible Electronics and Devices as Human–Machine Interfaces for Medical Robotics

A Flexible Ultrasound Array for Local Pulse Wave Velocity Monitoring

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