CN105147332A - Optoacoustic/ultrasonic dual mode endoscope based on miniature piezoelectric ultrasonic transducer arrays - Google Patents

Abstract

The invention discloses a photoacoustic/ultrasonic dual-mode endoscope based on a micro piezoelectric ultrasonic sensor array, comprising a micro piezoelectric ultrasonic sensor (PMUT) array probe 2, a PMUT array element 1, an integrated circuit 3, a plane lens 4, Focusing lens 6 , fiber coupling collimator 7 , single-mode fiber 8 , fiber FC/APC connector 9 , fiber 10 , signal line 11 and housing 12 . It is characterized in that it adopts miniature piezoelectric ultrasonic sensors, which have good compatibility with integrated circuits in the manufacturing process, and is easy to form an array; the use of sensor arrays makes the endoscope no need to rotate, improves the imaging speed, and can be used for Real-time imaging; multiple sensor arrays can effectively improve the signal-to-noise ratio of the signal, and can achieve deep focus scanning imaging. The invention can be widely used in the fields of medical endoscopic imaging, industrial flaw detection, etc., and has great application value especially in the aspects of identification of scar tissue in vivo, evaluation of ablation tissue damage, evaluation of atherosclerosis degree, and the like.

Description

Photoacoustic/ultrasonic dual-mode endoscope based on miniature piezoelectric ultrasonic sensor array

technical field

The invention relates to the technical field of non-destructive testing of medical endoscopes, in particular to a photoacoustic/ultrasonic dual-mode endoscope based on a micro piezoelectric ultrasonic sensor array, which can be applied to cardiac scar tissue identification, ablation tissue damage assessment, atherosclerosis Hardening degree assessment and so on.

Background technique

Atherosclerosis is the main cause of death in cardiovascular diseases. It is characterized by the appearance of yellow substances such as cholesterol and fat in the intima of the arteries, which reduces the elasticity of the arteries and narrows the lumen, often leading to thrombosis and blood supply disorders. Seriously endanger life and health. Therefore, in the examination of atherosclerosis, it is particularly important to determine the location of lesions, the distribution and composition of vulnerable plaques. Commonly used detection methods include angiography, intravascular ultrasound imaging, X-ray examination, etc. These imaging methods perform morphological imaging on blood vessels, and can only detect information such as the size and shape of atherosclerotic plaques, and cannot identify plaques. The composition of plaques, while photoacoustic imaging can not only detect the morphological information of atherosclerotic plaques, but also provide information on the composition of blood vessels and plaques.

Arrhythmia is also an important group of diseases in cardiovascular diseases, which is a clinical manifestation of abnormal cardiac electrical activity. The most common cause of an arrhythmia is an abnormal electrical path in the tissue of the heart. Usually, radiofrequency ablation is used to cause local endocardial and subendocardial myocardium coagulation necrosis by releasing radiofrequency current, so as to block abnormal conduction bundles and treat arrhythmia. Therefore, successful ablation therapy is dependent on the location of the ablation and the extent of the injury within the heart. However, since doctors cannot directly see the location of ablation and the degree of damage during the operation, a method that can determine the location and size of ablation and assess the degree of damage is needed. Due to its own advantages and characteristics, photoacoustic endoscopy just meets such needs.

Existing endoscopic technologies include electronic endoscopes and ultrasonic endoscopes. Electronic endoscopes can clearly present the morphological characteristics of the inner wall surface of biological tissues by using purely optical methods, but cannot reveal the detailed information below the inner wall surface of the tissue; Ultrasonic endoscope can image the part below the inner wall of biological tissue by using ultrasonic echo imaging, reflecting the difference in acoustic impedance, but the image contrast is low when imaging soft tissue, and functional information cannot be obtained.

As an emerging imaging technology, photoacoustic imaging combines the advantages of pure optical imaging and pure acoustic imaging, and obtains image information and functional characteristics with optical contrast through ultrasound. In theory, photoacoustic imaging overcomes the limitation of photon scattering in biological tissue to the resolution, so that photoacoustic imaging has very high spatial resolution and has a large transmission depth.

In addition, the Chinese patent "Miniature Photoacoustic Sensor Based on cMUT Ring Array" (CN103976743A) reports a capacitive micro-ultrasonic sensor (CMUT) that detects ultrasonic waves according to capacitance changes. Although this sensor has high sensitivity, the processing technology is very It is complex, and in order to achieve high sensitivity, a high bias voltage must be applied during the working process. When this technology is used for endoscopic imaging of living organisms, its safety needs to be further verified.

In addition, the Chinese patent "Endorectal Optical, Photoacoustic, Ultrasonic Multimodal Imaging Endoscope and Its Imaging Method" (CN103690141A) reports an optical, photoacoustic, and ultrasonic three-modal endoscopic imaging device and method, which realizes The integration and miniaturization of photoacoustic signal excitation components, ultrasonic signal excitation and acquisition components, and optical imaging components can simultaneously obtain the morphology, acoustic impedance difference and light absorption difference of rectal tissue. Another Chinese patent "An Intravascular Photoacoustic Ultrasound Dual-Modality Imaging System and Its Imaging Method" (CN103385758A) reports a photoacoustic/ultrasound dual-modal imaging system and method, which uses a different technology from the first The structure integrates and miniaturizes the emission and reception of laser excitation and ultrasound, and is used for simultaneous and same-region photoacoustic and ultrasound imaging in blood vessels. However, these two technologies need to be rotated and scanned point by point during the imaging process, the imaging speed is slow, and real-time imaging cannot be achieved, which limits their imaging applications in real-time identification of scar tissue and rapid assessment of ablation tissue damage during clinical operations. .

Contents of the invention

In order to overcome the shortcomings of the prior art above, the present invention provides a photoacoustic/ultrasonic dual-mode endoscope based on a miniature piezoelectric ultrasonic sensor array. On the one hand, in order to solve the problems of complex CMUT process and high bias voltage, the present invention adopts PMUT based on piezoelectric effect as the ultrasonic sensing unit. This sensor not only has high sensitive energy conversion effect and large sensing impedance And the process is relatively simple. On the other hand, in order to solve the problems that the existing photoacoustic endoscope needs to be rotated, the imaging speed is slow, and real-time imaging cannot be performed, the present invention uses a PMUT array to receive photoacoustic and ultrasonic signals, which greatly shortens the imaging time. The photoacoustic/ultrasonic dual-mode endoscope of the present invention can be widely used in the fields of medical endoscopic imaging and industrial flaw detection, especially in the identification of cardiac scar tissue, evaluation of ablation tissue damage, and evaluation of the degree of atherosclerosis. application value.

The present invention is realized through the following technical solutions: a photoacoustic ultrasonic dual-mode endoscope based on a miniature piezoelectric ultrasonic sensor array, including a PMUT array probe, a PMUT array element, an integrated circuit, a plane lens, a focusing lens, and an optical fiber coupling collimator Connectors, single-mode optical fibers, optical fiber FC/APC connectors, optical fibers, signal cables and housings. The optical fiber is inserted into one end of the optical fiber FC/APC connector, and the other end of the optical fiber FC/APC connector is connected to the fiber-coupled collimator through a single-mode optical fiber. Solid, PMUT array elements, integrated circuits, and signal lines are electrically connected in sequence, and are packaged together in the shell.

The PMUT array element is a vibrating film made on the surface of the substrate, which together with the substrate constitutes a PMUT array probe. The shape of the array element can be a planar structure such as a circle, a rectangle, or a polygon, or a three-dimensional structure such as a convex or concave shape. The back of the circuit board is electrically connected to the integrated circuit, and the integrated circuit leads out signals through signal lines.

The PMUT array probe is an annular hollow structure, and the plane lens is located in the annular hollow structure of the PMUT array probe. The plane lens and the PMUT array probe are located on the end face of the endoscope and tightly packaged to protect internal optical components.

The integrated circuit is composed of a driving circuit and a receiving circuit. The driving circuit is used to drive the sensor to emit ultrasonic waves. The receiving circuit is composed of a signal amplifier and a band-pass filter to receive the reflected ultrasonic signal and photoacoustic signal. Through the circuit integration process, the Integrated package of PMUT array probe and integrated circuit.

The centers of the optical fibers, optical fiber FC/APC connectors, single-mode optical fibers, fiber-coupled collimators, focusing lenses, PMUT array probes and planar lenses are all located on the same central axis, and are integrally packaged in the housing to form a coaxial structure .

The working process of the present invention is as follows: firstly, the pulsed laser light is introduced into the endoscope through the optical fiber, and then irradiates the biological tissue through the optical fiber FC/APC connector, single-mode optical fiber, optical fiber coupling collimator, focusing lens and plane lens; Secondly, the PMUT array receives the ultrasonic signal sent by the biological tissue, and the signal is filtered and amplified by the receiving circuit and then led to the external device by the signal line; then, the driving circuit drives the PMUT array to emit ultrasonic waves, and the ultrasonic echo is received by the PMUT array, and the echo signal passes through After the receiving circuit is filtered and amplified, it is led to the external device by the signal line; finally, the real-time imaging can be completed by repeating the above three steps.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention adopts a miniature piezoelectric ultrasonic sensor, and the processing size of the probe and the system size are in the order of micrometers and millimeters respectively. Compared with traditional ultrasonic sensors, it has the advantages of small volume, high array density, large bandwidth and high electromechanical conversion efficiency. , easy to realize miniaturization.

(2) The present invention integrates the micro-piezoelectric ultrasonic sensor and the integrated circuit with an integrated circuit process, and the two have very good compatibility, which reduces the difficulty of processing and improves the reliability and service life of the system.

(3) The present invention adopts a sensor array, so that the endoscope does not need to rotate during the imaging process, greatly improves the imaging speed, and can perform real-time imaging.

(4) The multi-element sensor array can effectively improve the signal-to-noise ratio of the signal, and can realize deep focus scanning imaging.

Description of drawings

Fig. 1 is a schematic side sectional view of the structure of the present invention.

Fig. 2 and Fig. 3 are end face schematic diagrams of the structure of the present invention.

FIG. 4 is a schematic diagram of the structure of the substrate and the PMUT array element.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

The photoacoustic/ultrasonic endoscope based on the miniature piezoelectric ultrasonic sensor array as shown in Figure 1 includes a PMUT array element 1, a PMUT array probe 2, an integrated circuit 3, a plane lens 4, a substrate 5, a focusing lens 6, and an optical fiber coupling Collimator 7, single-mode optical fiber 8, optical fiber FC/APC connector 9, optical fiber 10, signal line 11 and housing 12.

The optical fiber 10 is inserted into one end of the optical fiber FC/APC connector 9, and the other end of the optical fiber FC/APC connector 9 is connected to the fiber-coupled collimator 7 through a single-mode optical fiber 8, and the right side of the fiber-coupled collimator 7 is sequentially provided with a focusing lens 6 and a PMUT The array probe 2 and the plane lens 4 are mechanically fastened coaxially, the PMUT array element 1 is located on the surface of the substrate 5 and the base 5 together constitutes an annular array probe 2, and the PMUT array probe 2 and the plane lens 4 are both located on the end face of the endoscope and are coaxial Tight packaging is set, PMUT array element 1, integrated circuit 3, and signal line 11 are electrically connected in sequence; the optical fiber 10, optical fiber FC/APC connector 9, single-mode optical fiber 8, optical fiber coupling collimator 7, focusing lens 6, PMUT The centers of the array probe 2 and the planar lens 4 are both located on the same central axis, and are integrally packaged in the housing to form a coaxial structure.

As shown in Figures 2 and 3, the PMUT array element 1 is located on the surface of the substrate 5 and the substrate 5 together constitutes an annular array probe 2, the PMUT array probe 2 is an annular hollow structure, and the planar lens 4 is located in the annular hollow structure of the PMUT array probe, and the planar lens 4 is closely packaged with the PMUT array probe 2 to protect internal optical components.

As shown in Figure 4, the PMUT element 1 is a vibrating film on the surface of the base 5, the base 5 is a silicon substrate, a layer of silicon dioxide 13 is coated on the substrate, and then etched from the bottom of the silicon substrate at each element position. A groove is then plated on top of the silicon dioxide layer 13, a metal lower electrode 14, a piezoelectric film 15, and a metal upper electrode 16. The metal electrodes are conductive materials such as gold and aluminum. The piezoelectric film is aluminum nitride (AlN), PZT (leadZirconateTitanate) and other piezoelectric materials; the shape of the array element 1 can be a planar structure such as a circle, a rectangle, a polygon, or other three-dimensional structures such as a convex shape and a concave shape. structure, the back of the substrate 5 is electrically connected to the integrated circuit 3 through the micro connecting line 17, and the integrated circuit 3 is electrically connected to the signal line 11. The integrated circuit includes a driving circuit and a receiving circuit. The driving circuit is used to drive the sensor to emit ultrasonic waves. The receiving circuit is composed of a signal amplifier and a band-pass filter to receive the reflected ultrasonic signals and photoacoustic signals. Through the circuit integration process, the The upper and lower electrodes of the PMUT array element are connected to the integrated circuit and packaged in an integrated manner.

The PMUT array probe 2 can be designed on the substrate according to the requirements, and N PMUT array elements can be evenly arranged on a circular arc with a radian of 2π. It can be designed as a single-layer circular arc arrangement, or it can be designed as an M layer (M=1, 2,3,4,5...) arc arrangement, as shown in Figures 2 and 3.

The present invention mainly discloses and reports a photoacoustic/ultrasonic endoscope based on a miniature piezoelectric ultrasonic sensor array. Applying the endoscope of the present invention, combined with pulse laser, ultrasonic pulse transmitter receiver, data acquisition card and computer to form a photoacoustic/ultrasonic dual-mode endoscopic imaging system, can complete the structure and function of the heart, blood vessels, esophagus, intestinal tract, etc. Sexual endoscopic imaging. The photoacoustic/ultrasonic dual-mode endoscopic imaging system is not the main work of the present invention, so the external equipment other than the endoscope is not given a detailed introduction, and its technical details can refer to relevant documents.

Claims (6)

1. A photoacoustic/ultrasonic dual-mode endoscope based on a miniature piezoelectric ultrasonic sensor array, comprising a piezoelectric ultrasonic sensor PMUT array probe, a PMUT array element, an integrated circuit, a plane lens, a focusing lens, an optical fiber coupling collimator, Single-mode optical fiber, optical fiber FC/APC connector, optical fiber, signal line and housing; it is characterized in that PMUT is used as the sensing unit for receiving ultrasonic waves to form an array structure, wherein the optical fiber is inserted into one end of the optical fiber FC/APC connector, and the optical fiber FC/APC connector The other end is connected to the fiber-coupled collimator through a single-mode optical fiber. The fiber-coupled collimator, focusing lens, PMUT array probe and planar lens are mechanically fastened sequentially coaxially, and the PMUT array element, integrated circuit, and signal line are electrically connected in sequence. Commonly packaged in the shell. 2. a kind of photoacoustic/ultrasonic dual-mode endoscope based on the miniature piezoelectric ultrasonic transducer array according to claim 1, is characterized in that: described PMUT array element is the vibrating membrane that is made on the substrate surface, and substrate Together they form a PMUT array probe. The shape of the array elements can be circular, rectangular, polygonal and other planar structures, or other three-dimensional structures such as convex and concave. The back of the substrate is electrically connected to the integrated circuit, and the integrated circuit leads out signals through signal lines. 3. A kind of photoacoustic/ultrasonic dual-mode endoscope based on micro piezoelectric ultrasonic transducer array according to claim 1, it is characterized in that: described PMUT array probe is annular hollow structure, and plane lens is positioned at PMUT array probe In the annular hollow structure of the endoscope, and both are located at the end face of the endoscope. 4. A photoacoustic/ultrasonic dual-mode endoscope based on a miniature piezoelectric ultrasonic sensor array according to claim 1, wherein the integrated circuit is composed of a driving circuit and a receiving circuit, and the driving circuit is used for The drive sensor emits ultrasonic waves, and the receiving circuit is composed of a signal amplifier and a band-pass filter to receive the reflected ultrasonic signals and photoacoustic signals. The PMUT array probe and the integrated circuit are integrated into the package through the circuit integration process. 5. A photoacoustic/ultrasonic dual-mode endoscope based on a miniature piezoelectric ultrasonic sensor array according to claim 1, characterized in that: said optical fiber, optical fiber FC/APC connector, single-mode optical fiber, optical fiber coupling The centers of the collimator, the focusing lens, the PMUT array probe and the plane lens are all located on the same central axis, and are integrated in the housing to form a coaxial structure. 6. A photoacoustic/ultrasonic dual-mode endoscope based on a miniature piezoelectric ultrasonic sensor array according to claim 1, characterized in that: it can be composed of a pulse laser, an ultrasonic pulse transmitter receiver, a data acquisition card and a computer The photoacoustic/ultrasound dual-mode endoscopic imaging system is used to detect and identify scars of tissues in the body, assess the degree of atherosclerosis, or assess tissue damage during surgical ablation.