Acousto-optic-based time domain electric field sensor for magnetic resonance imaging applications.

An acousto-optic (AO)-based electric field sensor is presented for time domain measurement under magnetic resonance imaging (MRI). A fully MR-compatible sensor is designed and fabricated using a phase-shifted fiber Bragg grating mechanically coupled to a piezoelectric transducer. Mechanical resonance of the piezoelectric transducer is matched to the operating frequencies of commonly used MRI systems to increase the sensitivity of the sensor.

Application of Low Temperature Processed 0-3 Composite Piezoelectric Thick Films in Flexible, Non-planar, High Frequency Ultrasonic Devices.

Low-temperature, flexible, 0-3 composite piezoelectric materials can decrease the size, cost, and complexity of high-frequency acoustic devices on temperature sensitive substrates such as those in catheter based ultrasonic devices and acoustooptic sensors. In this paper, the application of low-temperature 0-3 connected composite thick films in flexible, non-planar, high frequency ultrasonic devices is reported. A flexible high-frequency ultrasound transducer and an acousto-optic radio-frequency (RF) field sensor are demonstrated utilizing PZT-based composite thick films.

Real-time device tracking under MRI using an acousto-optic active marker.

Purpose: This work aims to demonstrate the use of an "active" acousto-optic marker with enhanced visibility and reduced radiofrequency (RF) -induced heating for interventional MRI.

Methods: The acousto-optic marker was fabricated using bulk piezoelectric crystal and π-phase shifted fiber Bragg grating (FBGs) and coupled to a distal receiver coil on an 8F catheter. The received MR signal is transmitted over an optical fiber to mitigate RF-induced heating.

A Power-Efficient Bridge Readout Circuit for Implantable, Wearable, and IoT Applications.

A power-efficient bridge-to-digital sensing interface is proposed, which also offers immunity against power supply noise. The interface utilizes duty-cycling to reduce the static power consumption of resistive bridge sensors, which are commonly used in implantable, wearable, and internet of things (IoT) applications, such as intracranial pressure (ICP) sensing and blood pressure (BP) monitoring. The proposed interface uses a revised version of the pseudo-pseudo differential (PPD) topology with the ping-pong technique to reduce the complexity of traditional fully-differential counterparts.

Sensitivity and phase response of FBG based acousto-optic sensors for real-time MRI applications.

Fiber Bragg grating (FBG) based sensors have recently been introduced to the field of magnetic resonance imaging (MRI). Real-time MRI applications demand highly amplitude and phase sensitive MRI compatible sensors. Thus, a model and detailed analysis of FBG based ultrasound detection are required for designing better performing sensors.

Micro-mirror-array based off-axis flat lens for near-eye displays.

We developed an off-axis diffractive lens using a micro-mirror array on a flat substrate. MMA creates an on-axis converging beam from a 45 degrees off-axis diverging illumination beam and functions similar to a large and bulky elliptical mirror. The array consists of individual micro-mirrors with normal directions that vary across the component.

Acousto-Optic Catheter Tracking Sensor for Interventional MRI Procedures.

Objective: The objective of this paper is to introduce an acousto-optic optical fiber sensor for tracking catheter position during interventional magnetic resonance imaging (MRI) to overcome RF induced heating of active markers.

Methods: The sensor uses a miniature coil coupled to a piezoelectric transducer, which is in turn mechanically connected to an optical fiber. The piezoelectric transducer converts the RF signal to acoustic waves in the optical fiber over a region including a fiber Bragg grating (FBG).

Coagulation measurement from whole blood using vibrating optical fiber in a disposable cartridge.

In clinics, blood coagulation time measurements are performed using mechanical measurements with blood plasma. Such measurements are challenging to do in a lab-on-a-chip (LoC) system using a small volume of whole blood. Existing LoC systems use indirect measurement principles employing optical or electrochemical methods.