Modeling and Characterization of Pre-Charged Collapse-Mode CMUTs

Recently, the applications of ultrasound transducers expanded from high-end diagnostic tools to point of care diagnostic devices and wireless power receivers for implantable devices. These new applications additionally require that the transducer technology must comply to biocompatibility and manufacturing scalability. In this respect,...

Ultrasound Imaging with Pre-charged Collapse-Mode CMUTs

Capacitive micromachined ultrasonic transducers (CMUTs) with a built-in charge layer are known as a pre-charged CMUT. In our prior work, we have shown how to model and characterize the charges inside the pre-charged collapse-mode CMUT and conducted life-time test that showed that the charges trapped inside the dielectric were stable in the order...

A Comparative Study of Si3N4 and Al2O3 as Dielectric Materials for Pre-Charged Collapse-Mode CMUTs

Capacitive Micromachined Ultrasound Transducers (CMUTs) have many advantages compared to other ultrasonic transducer technologies, especially for implantable devices. However, they require a high bias voltage for efficient operation. To eliminate the need for an external bias voltage, a charge storage layer can be embedded in the dielectric....

Phase Distribution Efficiency of cm-Scale Ultrasonically Powered Receivers

In the domain of ultrasonically powered biomedical implants, there is an increasing interest in cm-scale ultrasonic receivers (RX). However, when a single-element transducer is used as the RX transducer, an uneven phase distribution across the RX area can significantly reduce the harvestable power. In this paper, we investigate the impact of...

An Ultrasonically Powered System Using an AlN PMUT Receiver for Delivering Instantaneous mW-Range DC Power to Biomedical Implants

Aluminum Nitride (AlN) Piezoelectric Micromachined Ultrasonic Transducers (PMUTs) are gaining interest for biomedical implant power due to biocompatibility and lowtemperature processing. However, due to the low piezoelectric coefficient of AlN PMUTs, storage capacitors are often used to accumulate ultrasonic power transferred over an extended...

Focused ultrasound neuromodulation on a multiwell MEA

Background<br/>Microelectrode arrays (MEA) enable the measurement and stimulation of the electrical activity of cultured cells. The integration of other neuromodulation methods will significantly enhance the application range of MEAs to study their effects on neurons. A neuromodulation method that is recently gaining more attention is focused...

Bulk Acoustic Wave Based Mocrfluidic Particle Sorting with Capacitive Micromachined Ultrasonic Transducers

The main limitation of acoustic particle separation for microfluidic application is its low sorting efficiency. This is due to the weak coupling of surface acoustic waves (SAWs) into the microchannel. In this work, we demonstrate bulk acoustic wave (BAW) particle sorting using capacitive micromachined ultrasonic transducers (CMUTs) for the first...

Time-efficient low power time/phase-reversal beamforming for the tracking of ultrasound implantable devices

Ultrasound (US) has recently gained attention for powering and communication with implantable devices due to its short wavelength and low attenuation. However, beam mis-alignments cause a sharp decrease in the amount of transferred power and quality of communication. This work investigates a telemetry protocol that relies on the difference in...

The long-term reliability of pre-charged CMUTs for the powering of deep implanted devices

Recently, focused ultrasound has been proposed to power deeply implanted medical devices. Almost exclusively, lead zirconate titanate (PZT) transducers are used to convert acoustic energy into electrical energy. Unfortunately, these lead containing devices cannot be hermetically encapsulated since that would block the ultrasound. We propose the...

A microwatt telemetry protocol for targeting deep implants

Implantable medical devices are becoming smaller and more deeply implanted in the human body for various applications (i.e., neurostimulation, drug delivery, bone fracture monitoring). Therefore, an efficient ultrasound power transfer link is needed to charge these devices. However, this is challenging because each ultrasound transducer has...

Pre-charged collapse-mode capacitive micromachined ultrasonic transducer (CMUT) for broadband ultrasound power transfer

Using ultrasound to power deeply implanted biomedical devices is a promising technique due to its low attenuation in body tissue and its short wavelength that allows precise focusing of the energy. Ultrasound energy harvesting conventionally has been done using lead zirconate titanate (PZT) ultrasound transducers, which uses the piezoelectric...

Schlieren visualization of focused ultrasound beam steering for spatially specific stimulation of the vagus nerve

In the bioelectronic medicine field, vagus nerve stimulation (VNS) is a promising technique that is expected to treat numerous inflammatory conditions, in addition to the currently FDA approved treatment for epilepsy, depression and obesity [1]. However, current VNS techniques are still limited in the spatial resolution that they can achieve,...