Wearable CMUT-Array for Online Monitoring of Blood Flow

Inhalt:
Currently more and more developments in medical diagnostics are focussed on online health monitoring which is also of interest for consumer products addressing professional and amateur sports. Known applications are the continuous measurement of pulse, blood pressure or electrocardiogram. However, to be able to detect critical health conditions at an early stage, more detailed information about blood flow is required. A typical approach for this diagnostic is the flow measurement using ultrasound, which can currently only be performed during clinical stay. Especially for high-risk patients, for example with thrombosis or cardiac insufficiency, a solution is needed, that is easy to use and does not limit the liveability. This application requires small wearable devices with integrated sensors in combination with integrated electronics and an intelligent signal processing and evaluation based on AI. Capacitive Micromachined Ultrasonic Transducers (CMUTs), which are characterized by a high sensitivity in receiving and a wide bandwidth based by their physical properties, are best suited for the classical sonography because of their natural matching to water. The improvement in the optimization of the CMUT structures at the Fraunhofer IPMS allows small apertures and arrays with a large number of elements with up to 30 MHz working frequency. The assembly of the CMUTs on silicon wafers allows the combination of analogue and digital circuit elements based on a CMOS technology for further integrations. The application of the CMUT arrays needs a preamplification close to the sensor for using with commercially available ultrasonic devices. Our first approach with 64 channels, presented in the past, takes a big volume and causes unwanted heating. Here we present our newest development of a small wearable array with up to 128 elements and included preamplifiers, what is significantly reduced in size and heating. First measurements on a medical body phantom show the applicability of the sensor array for medical diagnostics.