A multi-electrode cmut unit and a multi-frequency capacitive micromachined ultrasonic transducer

Abstract

The invention discloses a multi-electrode CMUT unit and a multi-frequency capacitive micro-machined ultrasonic transducer. The multi-electrode CMUT unit is composed of a silicon base, an insulating layer, a cavity, a vibrating film, an upper electrode, and an insulating film which are formed from bottom to top. The upper electrode is formed by a circular electrode, a first annular upper electrode,and a second annular upper electrode with a first interval and a second interval are arranged among thereof in a partitioning mode. A first convex ring and a second convex ring corresponding to the first interval and the second interval are integrally formed on the upper end face of the silicon base and protrude upwards. The ultrasonic transducer is of an array structure formed by a plurality ofmulti-electrode CMUT units. The silicon bases of the multi-electrode CMUT units integrally form a whole electrode. The circular electrodes of the multi-electrode CMUT units are connected in series toform a first positive electrode. The first annular upper electrodes of the multi-electrode CMUT units are connected in series to form a second positive electrode. The second annular upper electrodes of the multi-electrode CMUT units are connected in series to form a third positive electrode. The ultrasonic transducer can work in a plurality of frequency modes.

Description

technical field [0001] The invention relates to a capacitive micromachined ultrasonic transducer. In particular, it relates to a multi-electrode CMUT unit and a multi-frequency capacitive micromachine ultrasonic transducer working in an uncollapsed state. Background technique [0002] Increased skin permeability has major implications. For example, transdermal drug delivery is a method in which drugs are absorbed into the systemic circulation through the skin through capillaries to produce drug effects. It can avoid the first-pass effect of the liver, prolong the therapeutic effect of drugs with a short half-life, and maintain a constant rate of administration for a long time. medicine. However, current drugs using this method are limited, mainly due to the blocking effect of the stratum corneum of the skin. In addition, many research institutions at home and abroad are currently conducting research on transdermal extraction of interstitial fluid and analysis of interstit...

AI Technical Summary

Problems solved by technology

The disadvantage of operating the CMUT in this way is that when the diaphragm touches the substrate it can adhere to the substrate of the CMUT cell through van der Waals forces, although stable in collapsed mode, the diaphragm cannot be released and the CMUT cannot be reassembled. Work in the conventional mode (the diaphragm vibrates freely above the cavity); in addition, working in the collapse mode requires applying a higher voltage, which can easily lead to breakdown of the insulating layer on the CMUT substrate, and the charge accumulation of the insulating layer caused by this mode will Destroy the reliability of CMUT devices

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