Patent Publication Number: US-2017367681-A1

Title: Ultrasonic sensing apparatus and sensing method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Chinese Patent Application No. 201610476754.3 filed on Jun. 27, 2016, the contents of which are incorporated by reference herein. 
     FIELD 
     The subject matter herein generally relates to an ultrasonic sensing apparatus and a sensing method related to the ultrasonic sensing apparatus. 
     BACKGROUND 
     An ultrasonic sensing apparatus can sense a heart rate. The ultrasonic sensing apparatus can include a transmitting layer, a receiving layer, a readout layer, a first flexible printed circuit (FPC), a second FPC, and a third FPC. The transmitting layer generates ultrasonic signals output by the first FPC and the second FPC. The receiving layer receives ultrasonic signals reflected by an organism and converts the received ultrasonic signals into electrical signals. The readout layer analyzes the electrical signals to obtain vital signs of the organism. However, accuracy of the ultrasonic sensing apparatus would be improved by a better structure. Therefore, there is room for improvement in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Implementations of the present technology will now be described, by way of example only, with reference to the attached figures. 
         FIG. 1  is an exploded view of a first exemplary embodiment of an ultrasonic sensing apparatus comprising a transmitting layer and a readout layer. 
         FIG. 2  is a plan view of the readout layer of  FIG. 1 . 
         FIG. 3  is a waveform of the transmitting layer and the readout layer of  FIG. 1 . 
         FIG. 4  is an exploded view of a second exemplary embodiment of an ultrasonic sensing apparatus. 
         FIG. 5  is a cross-sectional view of the ultrasonic sensing apparatus of  FIG. 4 , the ultrasonic sensing apparatus comprising a plurality of transmitting sources. 
         FIG. 6  is a cross-sectional view of a first exemplary embodiment of the transmitting sources of  FIG. 5  with different amplitudes and a specified phase. 
         FIG. 7  is a cross-sectional view of a second exemplary embodiment of the transmitting sources of  FIG. 5  with a specified amplitude and a specified phase. 
         FIG. 8  is an exploded view of a third exemplary embodiment of an ultrasonic sensing apparatus comprising a transmitting layer and a readout layer. 
         FIG. 9  is a cross-sectional view of the ultrasonic sensing apparatus of  FIG. 8 . 
         FIG. 10  is a waveform of the transmitting layer and the readout layer of  FIG. 8 . 
         FIG. 11  is a partially exploded view of a fourth exemplary embodiment of an ultrasonic sensing apparatus. 
         FIG. 12  is a partially exploded view of a fifth exemplary embodiment of an ultrasonic sensing apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features. The description is not to be considered as limiting the scope of the embodiments described herein. 
     The term “substantially” is defined to be essentially conforming to the particular dimension, shape, or other feature that the term modifies, such that the component need not be exact. For example, “substantially cylindrical” means that the object resembles a cylinder, but can have one or more deviations from a true cylinder. The term “comprising” means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in a so-described combination, group, series, and the like. 
     The present disclosure is described in relation to an ultrasonic sensing apparatus. 
       FIG. 1  illustrates a first exemplary embodiment of an ultrasonic sensing apparatus  100 . The ultrasonic sensing apparatus  100  senses vital signs of humans, for example, a heart rate, a pulse, a blood pressure, and so on. The ultrasonic sensing apparatus  100  can be a tethered apparatus to paste onto skin, or can be embedded in a smart watch or a smart wrist strap. 
     The ultrasonic sensing apparatus  100  includes a transmitting layer  110 , a receiving layer  120 , a readout layer  130 , a first flexible circuit board  140 , a second flexible circuit board  150 , a third flexible circuit board  160 , and two adhesive layers  170 . In other embodiments, the ultrasonic sensing apparatus  100  includes an adhesive layer for sticking the ultrasonic sensing apparatus  100  onto a target. 
     The transmitting layer  110  includes a transmitting element  111 , a first conductive structure  113 , and a second conductive structure  115 . The transmitting element  111  is positioned between the first conductive structure  113  and the second conductive structure  115 . The first conductive structure  113  is positioned between the transmitting element  111  and the second flexible circuit board  150 . The second conductive structure  115  is positioned between the transmitting element  111  and the first flexible circuit board  140 . The first conductive structure  113  and the second conductive structure  115  together drive the transmitting element  111  to generate ultrasonic signals. In at least one embodiment, the transmitting element  111  is made of piezoelectric material, for example, polyvinylidene fluoride (PVDF), BaiO 3 , PbiO 3 , Pb(Zri)O 3 , plumbum scandium tantalite (PST), quartz, (Pb, Sm)iO 3 , PMN(Pb(MgNb)O 3 )—PT(PbiO 3 ), or PVDF-TrFE. In at least one embodiment, the first conductive structure  113  and the second conductive structure  115  are substantially flat. The first conductive structure  113  and the second conductive structure  115  can be formed on a surface of the transmitting element  111  by a vacuum sputtering manner, a painting manner, or a coating manner. In at least one embodiment, opposite surfaces of the transmitting element  111  can be conductively pasted to the first conductive structure  113  and the second conductive structure  115 . 
     The receiving layer  120  includes a receiving element  121  and a third conductive structure  123 . The receiving element  121  is positioned between the third conductive structure  123  and the two adhesive layers  170 . The receiving element  121  receives the ultrasonic signals reflected by the target. The third conductive structure  123  is positioned between the receiving element  121  and the third flexible circuit board  160 . The third conductive structure  123  converts the received ultrasonic signals into electric signals. In at least one embodiment, the receiving element  121  is also made of piezoelectric material, for example, the same material as that of the transmitting element  111 . In at least one embodiment, the third conductive structure  123  is substantially flat. In other embodiments, the third conductive structure  123  can include a plurality of sensing electrodes separated from each other. Each of the sensing electrodes can be a rectangular shape, a wave shape, a serrated shape, or other shape. The third conductive structure  123  can be formed on a surface of the receiving element  121  by a vacuum sputtering manner, a painting manner, or a coating manner. In at least one embodiment, the receiving element  121  can be conductively pasted to the third conductive structure  123 . 
     Referring to  FIG. 2 , the readout layer  130  can read electrical signals transmitted from the third conductive structure  123  and then transmit the electrical signals to a readout circuit (not shown) for calculating vital signs. The readout layer  130  is made of flexible material to adjust to the shape or surface of a target. The readout layer  130  includes a readout unit  132 . The readout unit  132  includes a plurality of input lines  131  extending along a first direction X, a plurality of output lines  133  extending along a second direction Y, a gate driver on panel (GOP)  134 , and a selector  136 . The second direction Y is perpendicular to the first direction X. Readout pixels  135  are defined by the output lines  131  intersecting with the output lines  133 . The input lines  131  are electrically connected to the GOP  134 , and the output lines  133  are electrically connected to the selector  136 . The GOP  134  selects the input lines  131  to turn on the readout pixels  135  for receiving electrical signals from the receiving layer  120 . The selector  136  selects the output lines  133  to provide a visual display of the electrical signals. In at least one embodiment, the selector  136  is a multiplexer. 
     The first flexible circuit board  140  is electrically connected to the second conductive structure  115 , and the second flexible circuit board  150  is electrically connected to the first conductive structure  113  and the second conductive structure  115 . The first flexible circuit board  140  provides a first specified voltage to the second conductive structure  115 , and the second flexible circuit board  150  provides a second specified voltage to the first conductive structure  113 . The second specified voltage is different from the first specified voltage. The third flexible circuit  160  provides data to the third conductive structure  123 . In at least one embodiment, the first flexible circuit board  140 , the second flexible circuit board  150 , and the third flexible circuit board  160  are insulated from each other. In other embodiments, the first flexible circuit board  140 , the second flexible circuit board  150 , and the third flexible circuit board  160  can be electrically connected. 
     One of the two adhesive layers  170  is positioned between the receiving element  121  and the readout layer  130  for pasting the receiving layer  120  on the readout layer  130 . Another of the two adhesive layers  170  is positioned between second conductive structure  115  and the readout layer  130  for pasting first conductive layer  113  on the readout layer  130 . 
     When the ultrasonic sensing apparatus  100  is in contact with a target, such as a wrist, a voltage difference between the first conductive structure  113  and the second conductive structure  115  causes the transmitting element  111  to vibrate to generate ultrasonic signals. The ultrasonic signals pass through the receiving layer  120  and the third flexible circuit board  160  to reach the target. The ultrasonic signals which reach the target are partially reflected by the target or by components within the target. The receiving layer  121  receives the reflected ultrasonic signals. The third conductive structure  123  converts the ultrasonic signals into electrical signals for transmission to the readout layer  130 . The target can be in direct contact with the third flexible circuit board  160 , or spaced apart from the third flexible circuit board  160  by a specified distance. 
       FIG. 3  illustrates a waveform of the ultrasonic sensing apparatus  100 . The ultrasonic sensing apparatus  100  works between a first period and a second period. The transmitting layer  110  generates the ultrasonic signals in the first period, and stops generating the ultrasonic signals during the second period. The readout layer  130  reads the electronic signals on the output lines  133  in the second period, and does not read the electronic signals on the output lines  133  in the first period. During the second period, the selector  136  completes one read operation corresponding to one of the readout pixels  135 . In detail, the GOP  134  sequentially turns on the readout pixel  135 , and the selector  136  sequentially reads the electronic signals on the output lines  133 . The selector  136  further calculates a difference between the received electronic signals and a specified value. Node A 1  represents a starting time of generating the ultrasonic signals of the transmitting layer  110 . Node B 1  represents a starting time of turning on the readout pixels  135  connected to the first input line  131  for receiving the electronic signals after conversion from the reflected ultrasonic signals. Node B 1 ′ represents an ending time of reading the electronic signals of the readout pixel  135  connected to the first output line  133 . Node C 1  represents a starting time of turning on the readout pixels  135  connected to the second input line  131  for receiving the electronic signals. Node C 1 ′ represents an ending time of reading the electronic signals of the readout pixel  135  connected to the second output line  133 . The time interval between the node B 1  and the node C 1  is more than 10 μs. 
     Based on the time sequence, a sensing depth of the ultrasonic sensing apparatus  100  is improved. 
       FIG. 4  illustrates a second exemplary embodiment of an ultrasonic sensing apparatus  200 . The ultrasonic sensing apparatus  200  according to the second exemplary embodiment is substantially the same as the ultrasonic sensing apparatus  100 . The ultrasonic sensing apparatus  200  includes a transmitting layer  210 , a receiving layer  220 , a readout layer  230 , a first flexible circuit board  240 , a second flexible circuit board  250 , a third flexible circuit board  260 , and two adhesive layers  270 . 
     The differences between the ultrasonic sensing apparatus  200  and the ultrasonic sensing apparatus  100  are hereinafter described. 
     The transmitting layer  210  includes a transmitting element  211 , a first conductive structure  213 , and a second conductive structure  215 . The transmitting element  211  is positioned between the first conductive structure  213  and the second conductive structure  215 . The first conductive structure  213  is positioned between the transmitting element  211  and the second flexible circuit board  250 . The second conductive structure  215  is positioned between the transmitting element  211  and the first flexible circuit board  240 . The first conductive structure  213  and the second conductive structure  215  together drive the transmitting element  211  to generate ultrasonic signals. 
     The first conductive structure  213  includes a plurality of first sensing electrodes  2131  parallel with each other, the plurality extends along the second direction Y. The second conductive structure  215  includes a plurality of second sensing electrodes  2151  parallel with each other, this plurality extends along the second direction Y. Each of the first sensing electrodes  2131  faces and is aligned with one second sensing electrode  2151 . The first sensing electrodes  2131  and the second sensing electrodes  2151  are substantially strip shaped. In at least one embodiment, the transmitting element  211  is made of the same piezoelectric material as hereinbefore described. In other embodiments, the first sensing electrodes  2131  and the second sensing electrodes  2151  can be a wave shape, or a serrated shape, or other shape. The first conductive structure  213  and the second conductive structure  215  can be formed on opposite surfaces of the transmitting element  211  by a vacuum sputtering manner, a painting manner, or a coating manner. In at least one embodiment, opposite surfaces of the transmitting element  211  can be conductively pasted to the first conductive structure  213  and the second conductive structure  215 . 
     The receiving layer  220  includes a receiving element  221  and a third conductive structure  223 . The receiving element  221  is positioned between the third conductive structure  223  and one of the two adhesive layers  270 . The receiving element  221  receives ultrasonic signals reflected by the target. The third conductive structure  223  is positioned between the receiving element  221  and the third flexible circuit board  260 . The third conductive structure  223  converts the received ultrasonic signals into electric signals. The third conductive structure  223  includes a plurality of third sensing electrodes  2231  parallel with each other, which extends along the second direction Y. Each of the third sensing electrodes  2231  faces and is aligned with one first sensing electrode  2131 . In at least one embodiment, the third sensing electrode  2231  is substantially strip shaped. In at least one embodiment, the receiving element  221  is made of the same piezoelectric material as hereinbefore described. In other embodiments, the third sensing electrodes  2231  are staggered in relation to the first sensing electrodes  2131 , the electrodes  2231  can be a wave shape, or a serrated shaped, or other shape. The third conductive structure  223  can be formed on a surface of the receiving element  221  by a vacuum sputtering manner, a painting manner, or a coating manner. In at least one embodiment, the receiving element  221  can be conductively pasted to the third conductive structure  223 . 
       FIG. 5  illustrates the first exemplary embodiment of the ultrasonic sensing apparatus  200  in cross section. Each first sensing electrode  2131  and a corresponding second sensing electrode  2151  together form a transmitting source  2101 , thereby forming a plurality of transmitting sources  2101  as the first conductive structure  213  and the second conductive structure  215 . Ultrasonic signals from all emitter components of all the transmitting sources  2101  can be generated simultaneously. 
       FIG. 6  illustrates the transmitting sources  2101  outputting with different specified amplitudes and a specified phase. The voltages applied on the first sensing electrodes  2131  and on the second sensing electrodes  2151  are different, thus the ultrasonic signals generated by different components of a transmitting source  2101  are in different amplitudes, but in a same specified phase. An intensity of the ultrasonic signals generated by two adjacent components in a transmitting source  2101  is enhanced at crossed points arranged in a line inclined with the transmitting element  211 . 
       FIG. 7  illustrates the transmitting sources  2101  with a specified amplitude and a specified phase. The voltage applied on the first sensing electrodes  2131  and the second sensing electrodes  2151  are the same, thus all of the ultrasonic signals generated by the transmitting sources  2101  are in a specified amplitude and a specified phase. An intensity of the ultrasonic signals generated by two adjacent components of within a transmitting source  2101  is enhanced at crossed points arranged in a line perpendicular to the transmitting element  211 . 
       FIG. 8  illustrates a third exemplary embodiment of the ultrasonic sensing apparatus  300 . The ultrasonic sensing apparatus  300  according to the second exemplary embodiment is substantially the same as the ultrasonic sensing apparatus  100 . The ultrasonic sensing apparatus  300  includes a transmitting layer  310 , a receiving layer  320 , a readout layer  330 , a first flexible circuit board  340 , a second flexible circuit board  350 , a third flexible circuit board  360 , and two adhesive layers  370 . 
     The differences between the ultrasonic sensing apparatus  300  and the ultrasonic sensing apparatus  100  are hereinafter described. 
     The transmitting layer  310  includes a transmitting element  311 , a first conductive structure  313 , and a second conductive structure  315 . The transmitting element  311  is positioned between the first conductive structure  313  and the second conductive structure  315 . The transmitting element  311  includes a plurality of transmitting units  3111  parallel with each other, the plurality extending along the second direction Y. The transmitting unit  3111  is substantially strip shaped. The first conductive structure  313  is positioned between the transmitting element  311  and the second flexible circuit board  350 . The second conductive structure  315  is positioned between the transmitting element  311  and the first flexible circuit board  340 . The first conductive structure  313  and the second conductive structure  315  together drive the transmitting element  311  to generate ultrasonic signals. The first conductive structure  313  includes a plurality of first sensing electrodes  3131  parallel with each other, the plurality extending along the second direction Y, and the second conductive structure  315  includes a plurality of second sensing electrodes  3151  parallel with each other, this plurality extending along the second direction Y. Each of the first sensing electrodes  3131  faces and is aligned with one second sensing electrode  3151 . Each of the transmitting units  3111  is positioned between one of the first sensing electrodes  3131  and the second sensing electrode  3151  which it faces. The first sensing electrodes  3131  and the second sensing electrodes  3151  are substantially strip shaped. In at least one embodiment, the transmitting element  111  is made of the same piezoelectric material as hereinbefore described. In other embodiments, the first sensing electrodes  3131  and the second sensing electrodes  3151  can be a wave shape, or a serrated shape, or other shape. The first conductive structure  313  and the second conductive structure  315  can be formed on opposite surfaces of the transmitting element  311  by a vacuum sputtering manner, a painting manner, or a coating manner. In at least one embodiment, opposite surfaces of the transmitting element  311  can be conductively pasted to the first conductive structure  313  and the second conductive structure  315 . 
     The receiving layer  320  includes a receiving element  321  and a third conductive structure  323 . The receiving element  321  is positioned between the third conductive structure  323  and one of the two adhesive layers  370 . The receiving element  321  receives the ultrasonic signals reflected by the target. The receiving element  321  includes a plurality of receiving units  3211  parallel with each other, the plurality extending along the second direction Y. Each of the receiving unit  3211  is substantially strip shaped. Each of the receiving units  3211  faces and is aligned with one first sensing electrode  3131 . The third conductive structure  323  is positioned between the receiving element  321  and the third flexible circuit board  360 . The third conductive structure  323  converts the received ultrasonic signals into electric signals. The third conductive structure  323  includes a plurality of third sensing electrodes  3231  parallel with each other, the plurality extending along the second direction Y. Each of the third sensing electrodes  3231  faces and is aligned with one first sensing electrode  3131 . In at least one embodiment, the third sensing electrode  3231  is substantially strip shaped. In at least one embodiment, the receiving element  321  is made of the same piezoelectric material as hereinbefore described. In other embodiments, the third sensing electrodes  3231  are staggered in relation to the first sensing electrodes  3131 , and can be a wave shape, or a serrated shaped, or other shape. The third conductive structure  323  can be formed on a surface of the receiving element  321  by a vacuum sputtering manner, a painting manner, or a coated manner. In at least one embodiment, the receiving element  321  can be conductively pasted to the third conductive structure  323 . 
       FIG. 9  illustrates a plan view of the ultrasonic sensing apparatus  300 . The first sensing electrode  3131 , the transmitting unit  3111 , and the second sensing electrode  3151  together form a transmitting source  3101 . All emitting components of the transmitting source  3101  simultaneously generate the ultrasonic signals. The ultrasonic signals generated by two adjacent transmitting sources  3101  will be enhanced at crossing points. 
       FIG. 10  shows a time sequence of the ultrasonic sensing apparatus  300 . The transmitting units  3101  output the ultrasonic signals in series during the first period. The first periods of the transmitting units  3101  are overlapped with each other. The readout layer  330  reads the electronic signals in the second period, and does not read the electronic signals in the first period. During the second period, the selector  336  completes one reading operation corresponding to one of the readout pixel  335 . 
       FIG. 11  a fourth exemplary embodiment of the ultrasonic sensing apparatus  400 . The ultrasonic sensing apparatus  400  according to the fourth exemplary embodiment is substantially the same as the ultrasonic sensing apparatus  100 . The ultrasonic sensing apparatus  400  includes a transmitting layer  410 , a receiving layer  420 , a readout layer  430 , a first flexible circuit board  440 , a second flexible circuit board  450 , a third flexible circuit board  460 , and two adhesive layers  470 . 
     The differences between the ultrasonic sensing apparatus  400  and the ultrasonic sensing apparatus  100  are hereinafter described. 
     The transmitting layer  410  includes a transmitting element  411 , a first conductive structure  413 , and a second conductive structure  415 . The transmitting element  411  is positioned between the first conductive structure  413  and the second conductive structure  415 . The first conductive structure  413  is positioned between the transmitting element  411  and the second flexible circuit board  450 . The second conductive structure  415  is positioned between the transmitting element  411  and the first flexible circuit board  440 . The first conductive structure  413  and the second conductive structure  415  together drive the transmitting element  411  to generate ultrasonic signals. The first conductive structure  413  includes a plurality of first sensing electrodes  4131  in a matrix, and the second conductive structure  415  includes a plurality of second sensing electrodes  4151  in a matrix. Each of the first sensing electrodes  4131  faces one second sensing electrode  4151 . The first sensing electrodes  4131  and the second sensing electrodes  4151  are substantially square shaped. In at least one embodiment, the transmitting element  111  is made of the same piezoelectric material as hereinbefore described. In other embodiments, the first sensing electrodes  4131  and the second sensing electrodes  4151  can be a wave shape, or a serrated shape, or other shape. The first conductive structure  413  and the second conductive structure  415  can be formed on a surface of the transmitting element  411  by a vacuum sputtering manner, a painting manner, or a coating manner. In at least one embodiment, opposite surfaces of the transmitting element  411  can be conductively pasted to the first conductive structure  413  and the second conductive structure  415 . 
     The receiving layer  420  includes a receiving element  421  and a third conductive structure  423 . The receiving element  421  is positioned between the third conductive structure  423  and the two adhesive layers  470 . The receiving element  421  receives the ultrasonic signals reflected by the target. The third conductive structure  423  is positioned between the receiving element  421  and the third flexible circuit board  460 . The third conductive structure  423  converts the received ultrasonic signals into electric signals. The third conductive structure  423  includes a plurality of third sensing electrodes  4231  in a matrix. Each of the third sensing electrodes  4231  faces one first sensing electrode  4131 . In at least one embodiment, the third sensing electrode  4231  is substantially square shaped. In at least one embodiment, the receiving element  421  is made of the same piezoelectric material as hereinbefore described. In other embodiments, the third sensing electrodes  4231  are staggered in relation to the first sensing electrodes  4131 , and can be a wave shape, or a serrated shape, or other shape. The third conductive structure  423  can be formed on a surface of the receiving element  421  by a vacuum sputtering manner, a painting manner, or a coating manner. In at least one embodiment, the receiving element  421  can be conductively pasted to the third conductive structure  423 . 
       FIG. 12  a fifth exemplary embodiment of the ultrasonic sensing apparatus  500 . The ultrasonic sensing apparatus  500  according to the fifth exemplary embodiment is approximately the same as the ultrasonic sensing apparatus  100 . The ultrasonic sensing apparatus  500  includes a readout layer  530 , a first flexible circuit board  540 , a second flexible circuit board  550 , a third flexible circuit board  560 , and two adhesive layers  570 . 
     The differences between the ultrasonic sensing apparatus  500  and the ultrasonic sensing apparatus  100  are hereinafter described. 
     The transmitting layer  510  includes a transmitting element  511 , a first conductive structure  513 , and a second conductive structure  515 . The transmitting element  511  is positioned between the first conductive structure  513  and the second conductive structure  515 . The transmitting element  511  includes a plurality of transmitting units  5111  in a matrix. The transmitting unit  5111  is substantially square shaped. The first conductive structure  513  is positioned between the transmitting element  511  and the second flexible circuit board  550 . The second conductive structure  515  is positioned between the transmitting element  511  and the first flexible circuit board  540 . The first conductive structure  513  and the second conductive structure  515  together drive the transmitting element  511  to generate ultrasonic signals. The first conductive structure  513  includes a plurality of first sensing electrodes  5131  parallel with each other, the plurality extending along the second direction Y, and the second conductive structure  515  includes a plurality of second sensing electrodes  5151  parallel with each other, this plurality extending along the second direction Y. Each of the first sensing electrodes  5131  faces and is aligned with one second sensing electrode  5151 . The first sensing electrodes  5131  and the second sensing electrodes  5151  are substantially strip shaped. In at least one embodiment, the transmitting element  111  is made of the same piezoelectric material as hereinbefore described. In other embodiments, the first sensing electrodes  5131  and the second sensing electrodes  5151  can be a wave shape, or a serrated shape, or other shape. The first conductive structure  513  and the second conductive structure  515  can be formed on a surface of the transmitting element  511  by a vacuum sputtering manner, a painting manner, or a coating manner. In at least one embodiment, opposite surfaces of the transmitting element  511  can be conductively pasted to the first conductive structure  513  and the second conductive structure  515 . 
     The receiving layer  520  includes a receiving element  521  and a third conductive structure  523 . The receiving element  521  is positioned between the third conductive structure  523  and the two adhesive layers  570 . The receiving element  521  receives the ultrasonic signals reflected by the target. The receiving element  521  includes a plurality of receiving units  5211  in a matrix. The receiving unit  5211  is substantially square shaped. Each of the receiving units  5211  faces one transmitting unit  5111 . The third conductive structure  523  is positioned between the receiving element  521  and the third flexible circuit board  560 . The third conductive structure  523  converts the received ultrasonic signals into electric signals. The third conductive structure  523  includes a plurality of third sensing electrodes  5231  parallel with each other, the plurality extending along the second direction Y. Each of the third sensing electrodes  5231  faces and is aligned with one first sensing electrode  5131 . In at least one embodiment, the third sensing electrode  5231  is substantially strip shaped. In at least one embodiment, the receiving element  521  is made of the same piezoelectric material as hereinbefore described. In other embodiments, the third sensing electrodes  5231  are staggered in relation to the first sensing electrodes  5131 , and can be a wave shape, or a serrated shape, or other shape. The third conductive structure  523  can be formed on a surface of the receiving element  521  by a vacuum sputtering manner, a painting manner, or a coating manner. In at least one embodiment, the receiving element  521  can be conductively pasted to the third conductive structure  523 . 
     While various exemplary and preferred embodiments have been described, the disclosure is not limited thereto. On the contrary, various modifications and similar arrangements (as would be apparent to those skilled in the art) are intended to also be covered. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.