Fingerprint sensor system including metamaterials

Abstract

The device may include a cover layer, a first metamaterial layer near the cover layer (or in the cover layer), a light source system configured to provide light to the first metamaterial layer, and a receiver system. The first metamaterial may include nanoparticles configured to generate ultrasonic waves when irradiated by light. The receiver system may include an ultrasonic receiver system configured to receive ultrasonic waves reflected from a target object in contact with a surface of the cover layer or near a surface of the cover layer. The control system may be configured to receive an ultrasonic receiver signal corresponding to the ultrasonic wave reflected from the target object from the ultrasonic receiver system, and perform an authentication process and / or an imaging process based at least in part on the ultrasonic receiver signal.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to non-provisional application No. 16 / 691,416, filed on November 21, 2019, entitled “FINGERPRINT SENSOR SYSTEM INCLUDING METAMATERIAL,” which is assigned to the assignee of the present application and is expressly incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to biometric devices and methods, including but not limited to ultrasound sensor systems and optical sensor systems. Background Art

[0004] Ultrasonic fingerprint sensor systems or optical fingerprint sensor systems can be good means for obtaining a biometric image of a target object (such as a finger). Under-display ultrasonic fingerprint sensors have recently been commercialized in the market. Although some previously deployed fingerprint sensor systems are generally satisfactory for some applications, there is still a need for improved fingerprint sensor systems. Summary of the invention

[0005] The systems, methods and devices of the present disclosure each have several innovative aspects, no single one of which is responsible for all the desirable attributes disclosed herein.

[0006] One innovative aspect of the subject matter described in the present disclosure can be implemented in a device. In some examples, the device may include a cover layer, a first metamaterial layer within or proximate to the cover layer, a light source system configured to provide light to the first metamaterial layer, and a receiver system including an ultrasound receiver system configured to receive ultrasound waves reflected from a target object in contact with or proximate to a surface of the cover layer. The first metamaterial may include nanoparticles configured to resonate and generate ultrasound waves when illuminated by light. In some embodiments, a mobile device may be or may include the device. For example, a cellular phone may be or may include the device.

[0007] According to some embodiments, the light source system may include a waveguide proximate to the first metamaterial layer. The waveguide may be configured to receive light from the light source and provide the light to the first metamaterial layer. In some examples, the light source system may include a light source configured to emit light including a resonant frequency of at least some of the nanoparticles.

[0008] According to some examples, the apparatus includes a control system. The control system may include one or more general purpose single-chip or multi-chip processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or a combination thereof.

[0009] In some embodiments, the control system can be configured to control the light source system to cause the nanoparticles to emit ultrasound waves in the range of 1 MHz to 30 MHz. According to some embodiments, the control system can be configured to receive ultrasound receiver signals corresponding to ultrasound waves reflected from the target object from the ultrasound receiver system, and perform an authentication process and / or an imaging process based at least in part on the ultrasound receiver signals.

[0010] According to some examples, the cover layer may be or may include an optically opaque pressboard or an optically translucent pressboard. However, in some examples, the cover layer may be optically transparent.

[0011] Some embodiments may include a second metamaterial layer configured to convert acoustic waves into light. In some such examples, the cover layer may include the second metamaterial layer.

[0012] In some embodiments, the receiver system may include an optical receiver system. According to some such embodiments, a single layer of the receiver system may include a portion of the optical receiver system and a portion of the ultrasonic receiver system. Some such embodiments may also include a control system. In some examples, the control system may be configured to receive a light receiver signal from the optical receiver system and perform an authentication process and / or an imaging process based at least in part on the light receiver signal. In some cases, at least some of the light receiver signals may correspond to light emitted by the second metamaterial. In some examples, the control system may be configured to control the light source system to induce photoacoustic emissions from the target object. According to some examples, at least some of the optical receiver signals may correspond to light reflected from the target object. In some examples, the control system may be configured to receive an ultrasonic receiver signal corresponding to an ultrasonic wave reflected from the target object from the ultrasonic receiver system, and perform an authentication process and / or an imaging process based at least in part on the ultrasonic receiver signal.

[0013] According to some examples, the ultrasound receiver system may include a piezoelectric layer. In some cases, the piezoelectric layer may include microparticles and / or nanoparticles in a piezoelectric polymer matrix. For example, the microparticles and / or nanoparticles may include a ferroelectric material.

[0014] Other innovative aspects of the subject matter described in the present disclosure may be implemented in a method. The method may involve controlling a light source system to emit light that causes at least some of the nanoparticles of the first metamaterial layer to emit ultrasonic waves. The method may involve receiving a first ultrasonic receiver signal from an ultrasonic receiver system corresponding to ultrasonic waves generated by the nanoparticles and reflected from a target object. The method may involve performing an imaging process and / or an authentication process based at least in part on the first ultrasonic receiver signal.

[0015] According to some examples, the method may involve controlling a light source system to illuminate at least a portion of a target object. In some examples, the method may involve receiving an optical receiver signal corresponding to light reflected from the target object from an optical receiver system, and performing an imaging process or an authentication process based at least in part on the optical receiver signal.

[0016] In some embodiments, the method may involve controlling a light source system to induce photoacoustic emissions from at least a portion of the target object. In some examples, the method may involve receiving a second ultrasound receiver signal corresponding to the ultrasound waves generated via the photoacoustic emissions from an ultrasound receiver system, and performing an imaging process and / or an authentication process based at least in part on the second ultrasound receiver signal.

[0017] Some or all of the operations, functions, and / or methods described herein may be performed by one or more devices according to instructions (e.g., software) stored on one or more non-transitory media. Such non-transitory media may include memory devices such as those described herein, including but not limited to random access memory (RAM) devices, read-only memory (ROM) devices, etc. Therefore, some innovative aspects of the subject matter described in this disclosure may be implemented in non-transitory media having software stored thereon.

[0018] For example, the software may include instructions for controlling one or more devices to perform a method, the method involving controlling a light source system to emit light that causes at least some of the nanoparticles of the first metamaterial layer to emit ultrasonic waves. The method may involve receiving a first ultrasonic receiver signal from an ultrasonic receiver system corresponding to the ultrasonic waves generated by the nanoparticles and reflected from the target object. The method may involve performing an imaging process and / or an authentication process based at least in part on the first ultrasonic receiver signal.

[0019] According to some examples, the method may involve controlling a light source system to illuminate at least a portion of a target object. In some examples, the method may involve receiving an optical receiver signal corresponding to light reflected from the target object from an optical receiver system, and performing an imaging process or an authentication process based at least in part on the optical receiver signal.

[0020] In some embodiments, the method may involve controlling a light source system to induce photoacoustic emissions from at least a portion of the target object. In some examples, the method may involve receiving a second ultrasound receiver signal corresponding to the ultrasound waves generated via the photoacoustic emissions from an ultrasound receiver system, and performing an imaging process and / or an authentication process based at least in part on the second ultrasound receiver signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Details of one or more embodiments of the subject matter described in this specification are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. It should be noted that the relative sizes of the following drawings may not be drawn to scale. The same reference numerals and names in different drawings indicate the same elements.

[0022] Figure 1 is a block diagram illustrating example components of an apparatus according to some disclosed embodiments.

[0023] Figure 2 Another example of an apparatus configured to perform at least some of the methods disclosed herein is shown.

[0024] Figure 3 Another example of an apparatus configured to perform at least some of the methods disclosed herein is shown.

[0025] Figure 4 are flow charts that provide examples of methods that may be performed via some disclosed embodiments.

[0026] Figure 5 Examples of subepidermal features are shown.

[0027] Figure 6 An example of a receiver system 108 is shown that includes an optical receiver portion and an ultrasonic receiver portion.

[0028] Fig. 7A Another example of an apparatus configured to perform at least some of the methods disclosed herein is shown.

[0029] Figure 7B Shows Fig. 7A An alternative example of a layer of a device.

[0030] Figure 8 Aspects of a 4×4 pixel array of sensor pixels for an ultrasound sensor system are representatively depicted.

[0031] Fig.9A and Fig. 9B An example arrangement of ultrasound transmitters and receivers in an ultrasound sensor system is shown, wherein other arrangements are possible. DETAILED DESCRIPTION

[0032] For the purpose of describing the innovative aspects of the present disclosure, the following description is directed to certain embodiments. However, one of ordinary skill in the art will readily recognize that the teachings herein may be applied in a variety of different ways. The described embodiments may be implemented in any device, apparatus, or system that includes the biometric system disclosed herein. In addition, it is contemplated that the described embodiments may be included in or associated with a variety of electronic devices, such as, but not limited to: mobile phones, multimedia Internet-enabled cellular phones, mobile television receivers, wireless devices, smartphones, smart cards, wearable devices (such as bracelets, armbands, wristbands, rings, headbands, patches, etc.), devices, personal data assistants (PDAs), wireless email receivers, handheld or portable computers, netbooks, notebooks, smart books, tablet computers, printers, copiers, scanners, fax machines, global positioning system (GPS) receivers / navigators, cameras, digital media players (such as MP3 players), camcorders, game consoles, watches, clocks, calculators, television monitors, flat panel displays, electronic reading devices (e.g., e-readers), mobile health devices, computer monitors, automotive displays (including odometer and speedometer displays, etc.), cockpit controls and / or displays, camera vision displays (such as the display of a rearview camera in a vehicle), electronic photographs, electronic billboards or signs, projectors, architectural structures, microwave ovens, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, radios, portable memory chips, washers, dryers, washer / dryers, parking meters, packaging (such as in electromechanical systems (EMS) applications, including microelectromechanical systems (MEMS) applications, as well as non-EMS applications), aesthetic structures (such as the display of an image on a piece of jewelry or clothing), and various EMS devices. The teachings herein may also be used in a variety of applications, such as, but not limited to, electronic switching devices, radio frequency filters, sensors, accelerometers, gyroscopes, motion sensing devices, magnetometers, inertial components of consumer electronics, parts of consumer electronics, steering wheels or other automotive parts, varactor diodes, liquid crystal devices, electrophoretic devices, drive schemes, manufacturing processes, and electronic test equipment. Therefore, the teachings are not intended to be limited to the embodiments depicted only in the accompanying drawings, but have a wide range of applicability, which will be apparent to one of ordinary skill in the art.

[0033] In many cases, ultrasonic fingerprint sensors can obtain a suitable biometric image of a finger or other target object. However, some insonification processes have significant power requirements. Some films used for screen protection can significantly attenuate ultrasonic signals. In addition, pulsing high voltages to piezoelectric transmitters can introduce unwanted electrical noise into the system.

[0034] Some such embodiments use light at or near an outer surface, such as a platen surface or a cover layer, to generate ultrasonic or acoustic energy waves using photoacoustically activated nanoparticles. For example, light may be provided to a leaky optical waveguide and may be guided through a nanoparticle layer. Alternatively or additionally, the waveguide itself may include nanoparticles. Some of the disclosed sensor systems may include nanoparticles in a platen or a cover layer. The nanoparticles may resonate and generate ultrasonic waves via thermoelastic heating. Some of the generated ultrasonic waves may propagate toward the outer surface, where they interact with the structure of the target object, such as the ridges and valleys of a finger in contact with the outer surface. Ultrasonic waves contacting the air space corresponding to the valley may be reflected and may be detected by an ultrasonic receiver array. The control system may be configured to perform an authentication process and / or an imaging process based at least in part on ultrasonic receiver signals received from an ultrasonic receiver array. Some embodiments may include a piezoelectric ultrasonic receiver, transmitter, or transceiver layer that includes micron ferroelectric particles or nano ferroelectric particles.

[0035] Some embodiments may also include an array of optical receivers. Some such embodiments may include both optical receivers and ultrasonic receivers in a single receiver layer. The control system may be configured to control the light source system to illuminate at least a portion of the target object. The control system may be configured to perform an authentication process and / or an imaging process based at least in part on the light receiver signals received from the array of optical receivers. In some such embodiments, the control system may be configured to control the light source system to induce photoacoustic emissions from the target object. In some examples, the device may include a second metamaterial layer configured to convert acoustic waves into light.

[0036] Certain embodiments of the subject matter described in the present disclosure may be implemented to achieve one or more of the following potential advantages. By including microparticles or nanoparticles of a ferroelectric material having a high electromechanical coupling coefficient with a suitable piezoelectric polymer matrix (such as polyvinylidene fluoride (PVDF) or polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymer), a higher signal can be obtained from a piezoelectric receiver or transmitter. Some of the disclosed ultrasound sensor systems with photoacoustically activated nanoparticles, and those configured to induce photoacoustic emission from a target object, do not require a piezoelectric transmitter. In such a sensor system, high voltage pulses do not need to be provided to the piezoelectric transmitter, and associated electrical noise is not caused. A sensor system configured to perform an authentication process and / or an imaging process based at least in part on an optical receiver signal is able to improve the attenuation of ultrasound signals caused by some films used for screen protection.

[0037] Figure 11 is a block diagram illustrating example components of an apparatus according to some disclosed embodiments. In this example, the apparatus 100 includes a cover layer 102 and a first metamaterial layer 104. In some examples, the cover layer 102 can be optically transparent. However, in some embodiments, the cover layer 102 can be optically opaque or optically translucent. For example, the cover layer 102 can be or can include an optically opaque pressboard or an optically translucent pressboard.

[0038] According to the embodiment, the first metamaterial layer 104 includes nanoparticles configured to resonate and generate ultrasonic waves when illuminated by light. The first metamaterial layer 104 may include such nanoparticles dispersed in an adhesive material (such as a transparent adhesive material). In some embodiments, the first metamaterial layer 104 may be close to the cover layer 102, and in some examples, may be adjacent to the cover layer 102. However, in some examples, at least some of the nanoparticles (and / or other metamaterials) may be present in the cover layer 102.

[0039] In this example, the device 100 includes a light source system 106. According to some embodiments, the light source system 106 is configured to provide light to the first metamaterial layer 104. According to some embodiments, the light source system 106 may include one or more light sources configured to emit light including the resonant frequency of at least some of the nanoparticles. Relatively large particles typically resonate at relatively low frequencies, and relatively small particles typically resonate at relatively high frequencies. It may be advantageous to vibrate a determined size of the particles at one or more operating frequencies of interest. In some examples, the light source may be or may include one or more light emitting diodes (LEDs) and / or one or more laser diodes. According to some embodiments, the LED may be an organic light emitting diode (OLED). In some embodiments, the light source may be configured to provide light that is invisible to the human eye, such as infrared light or ultraviolet light.

[0040] In some examples, the light source system 106 may include a waveguide proximate to the first metamaterial layer 104. The waveguide may be configured to receive light from the light source and provide the light to the first metamaterial layer 104. For example, the light source system 106 may include a light source and a leaky light waveguide. Light from the light source may be provided to the leaky light waveguide and may be directed toward (e.g., upward) the cover layer 102 by nanoparticles in the first metamaterial layer 104 and / or the cover layer 102. Alternatively or additionally, the waveguide itself may include such nanoparticles.

[0041] According to some examples, the light source may be or may include a pulsed light source. Some such embodiments may include a control system 110. In some such embodiments, the control system 110 may be configured to control the light source system so that the nanoparticles emit ultrasonic waves in the range of 5 MHz to 30 MHz. However, in other embodiments, the control system 110 may be configured to cause the nanoparticles to emit ultrasonic waves in a frequency range higher or lower than 5 MHz to 30 MHz. For example, in some embodiments, the control system 110 may be configured to control the light source system so that the nanoparticles emit ultrasonic waves in the range of 1 MHz to 5 MHz (e.g., in the range of 1 MHz to 2.5 MHz). Such an embodiment may cause the nanoparticles of the first metamaterial layer 104 to emit ultrasonic waves in a range suitable for an ultrasonic imaging process and / or an authentication process.

[0042] In this example, the device 100 includes a receiver system 108. In some embodiments, the receiver system 108 includes an ultrasound receiver system. In some such embodiments, the control system can be configured to receive an ultrasound receiver signal from the ultrasound receiver system corresponding to ultrasound waves reflected from a target object in contact with or near the surface of the cover layer 102. The control system can be configured to perform at least one of an authentication process or an imaging process based at least in part on the ultrasound receiver signal.

[0043] In some such embodiments, the ultrasound receiver system includes a piezoelectric material, such as a PVDF polymer or a PVDF-TrFE copolymer. In some embodiments, a separate piezoelectric layer can be used as an ultrasound transmitter. In some embodiments, a single piezoelectric layer can be used as a transmitter and receiver. Other embodiments can have an ultrasound receiver but no ultrasound transmitter. In some embodiments, other piezoelectric materials can be used in the piezoelectric layer, such as aluminum nitride (AlN) or lead zirconate titanate (PZT).

[0044] According to some examples, the piezoelectric material may include microparticles or nanoparticles in a piezoelectric polymer matrix. In some such embodiments, the microparticles and / or nanoparticles may include ferroelectric materials. In some examples, the microparticles and / or nanoparticles may include ZnO, PZT, and / or BaTiO3. According to some embodiments, the microparticles and / or nanoparticles may have a diameter in the range of 3nm to 200nm.

[0045] In some cases, receiver system 108 may include an optical receiver system. According to some such embodiments, a single layer of receiver system 108 may include portions of an optical receiver system and portions of an ultrasound receiver system. Some examples are described below.

[0046] The control system 110 may include one or more general purpose single-chip or multi-chip processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or a combination thereof. The control system 110 may also include (and / or be configured to communicate with) one or more memory devices, such as one or more random access memory (RAM) devices, read-only memory (ROM) devices, etc. Thus, although the memory system is not Figure 1 100 is not shown, but the device 100 may have a memory system including one or more memory devices. The control system 110 is capable of receiving and processing data from the receiver system 108. If the device 100 includes an ultrasonic transmitter, the control system 110 is capable of controlling the ultrasonic transmitter 108. In some embodiments, the functionality of the control system 110 may be divided between one or more controllers or processors, such as between a dedicated sensor controller and an application processor of a mobile device.

[0047] Some embodiments of the apparatus 100 may include an interface system 112. In some examples, the interface system may include a wireless interface system. In some embodiments, the interface system may include a user interface system, one or more network interfaces, one or more interfaces between the control system 110 and a memory system, and / or one or more interfaces between the control system 110 and one or more external device interfaces (e.g., a port or an application processor).

[0048] The interface system 112 may be configured to provide communication (which may include wired or wireless communication, such as electrical communication, radio communication, etc.) between components of the apparatus 100. In some such examples, the interface system 112 may be configured to provide communication between the control system 110 and the receiver system 108 and / or the light source system 106. According to some such examples, a portion of the interface system 112 may couple at least a portion of the control system 110 to the receiver system 108 and / or the light source system 106, for example, via a conductive material. If the apparatus 100 includes an ultrasonic transmitter 108 that is separate from the receiver system 108, the interface system 112 may be configured to provide communication between at least a portion of the control system 110 and the ultrasonic transmitter 108.

[0049] According to some examples, the interface system 112 can be configured to provide communication between the apparatus 100 and other devices and / or humans. In some such examples, the interface system 112 may include one or more user interfaces. In some examples, the interface system 112 may include one or more network interfaces and / or one or more external device interfaces (such as one or more universal serial bus (USB) interfaces). In some embodiments, the apparatus 100 may include a memory system. In some examples, the interface system 112 may include at least one interface between the control system 110 and the memory system.

[0050] The device 100 can be used in a variety of different environments, some examples of which are disclosed herein. For example, in some embodiments, a mobile device may include at least a portion of the device 100. In some cases, the mobile device may be a cellular phone, a tablet device, etc. In some embodiments, a wearable device may include at least a portion of the device 100. For example, the wearable device may be a bracelet, an armband, a wristband, a ring, a headband, or a patch. In some embodiments, the control system 110 may be located in more than one device. For example, a portion of the control system 110 may be located in a wearable device, and another portion of the control system 110 may be located in another device, such as a mobile device (e.g., a smartphone or a tablet computer). In some such examples, the interface system 112 may also be located in more than one device.

[0051] Figure 2 Another example of an apparatus configured to perform at least some of the methods disclosed herein is shown. Figure 2 The device 100 can be considered as Figure 1 1. An example of the device 100 shown. In this example, the light source system 106 includes a light source 206 and a waveguide 208. According to this example, the first metamaterial layer 104 is located between the waveguide 208 and the cover layer 102, and the target object 202 is placed on the cover layer 102. In this example, the target object 202 is a finger. (As used herein, the term "finger" has a sufficiently broad meaning and can refer to any finger, including a thumb. Therefore, the term "fingerprint" has a sufficiently broad meaning and can refer to the fingerprint of any finger, including a thumbprint.)

[0052] In some implementations, the light source 206 includes at least one LED and / or at least one laser diode. According to this example, the waveguide 208 is configured to guide at least some of the light provided by the light source 206 to the first metamaterial layer 104 .

[0053] In this embodiment, the first metamaterial layer 104 includes nanoparticles 204 configured to resonate and generate ultrasound waves when illuminated by light. In this example, the first metamaterial layer 104 includes an adhesive material in which the nanoparticles 204 are suspended. In some such examples, the adhesive material may include a transparent material, such as a transparent polymer adhesive. According to some examples, the nanoparticles 204 may include gold nanoparticles. In some cases, the nanoparticles 204 may include carbon nanoparticles. According to some such examples, the nanoparticles 204 may include the type of carbon black particles used in ink (India ink). In some examples, the nanoparticles 204 may be as small as 10 nanometers, while in other examples, the size of the nanoparticles 204 may be 100 nanometers or larger.

[0054] exist Figure 2 In the example shown, nanoparticles 204 are used for ultrasound penetration. In some examples, light source 206 can be configured to emit light including the resonant frequency of at least some nanoparticles 204. According to some examples, light 210 includes the resonant frequency of nanoparticles 204. Therefore, the irradiation of light 210 causes nanoparticles 204 to expand.

[0055] Alternatively or additionally, in some examples, the pulse duration and / or time interval between the light pulses emitted by the light source 206 determines the frequency of the ultrasonic waves 212 emitted by the nanoparticles when the nanoparticles expand when irradiated and contract between pulses. In some examples, the light pulses emitted by the light source 206 have a pulse duration in the range of 1 μs to 5 μs (e.g., 3 μs). In some such examples, the light pulses emitted by the light source 206 have a power density in the range of 0.20 mW / mL to 1.0 mW / mL (e.g., 0.7 mW / mL).

[0056] In the photoacoustic system of device 100, there is a small waiting time while the nanoparticles heat up, expand, and then collapse. This waiting time is well defined in the literature, for example, in Chao Tian, ​​Zhixing Xie, Mario L. Fabilli, Shengchun Liu, Cheng Wang, Qian Cheng, and Xueding Wang, "Dual-pulsenon linear photoacoustic technique: a practical investigation" (Optical Society of America, 2015) (hereinafter referred to as "Tian et al."). This waiting time should be taken into account when determining appropriate standards for the photoacoustic system (e.g., appropriate values ​​of rangegate delay for obtaining data from receiver system 108). As described by Tian et al., the waiting time is expected to be at least as long as the "stress relaxation time" τ s Same length, and no longer than the thermal relaxation time τ th The thermal relaxation time is the time required for a target to cool to 50% of its excited state temperature and can be expressed as follows:

[0057]

[0058] In Formula 1, d represents the diameter of the target, which in some examples may be the spot size of the light source. In some disclosed embodiments, d may be in the range of 1 μm to 20 μm. In Formula 1, α th represents the thermal diffusivity. The thermal diffusivity will vary depending on the material used to form the nanoparticles and the binder in which the nanoparticles are dispersed. In some examples, the thermal diffusivity can be within 0.05 mm 2 / sec to 2.0 mm 2 In one example, assuming 0.13 mm 2 / sec thermal diffusivity and a target volume of 10 μm, the thermal relaxation time can be calculated from Equation 1 to be 769 μs.

[0059] The stress relaxation time can be expressed as follows:

[0060]

[0061] In Formula 2, d represents the diameter of the target, and c LIn one example, assuming that the longitudinal sound velocity is 1500 m / s (a typical value for coating adhesives) and the target volume is 10 μm, the stress relaxation time that can be calculated according to Formula 2 is 6.7 μs.

[0062] Therefore, in this example, the waiting time for the nanoparticles to heat, expand, and then collapse will be in the range of 6.7 nanoseconds to 769 microseconds. According to the photoacoustic literature including Tian et al., the light pulse duration should be less than any time, for example, in the range of 1 μs to 5 μs. For embodiments where the light source system 106 is configured to emit a series of light pulses, in this example, the interval between light pulses should be at least 769 μs to avoid ablation and cavitation.

[0063] Assume that Figure 2 or Figure 3 For the device configured as shown, if t0 is the time when the light source system 106 emits a light pulse, the elapsed time between t0 and the time when the light pulse reaches the nanoparticle is very small and can be ignored. In this example, the nanoparticle 204 will begin to emit ultrasonic waves approximately 6.7 μs after t0. The appropriate range gating delay after t0 can be determined by adding this waiting time to the length of time it takes for the emitted ultrasonic wave 212 to propagate from the nanoparticle 204 to the target area and return to the receiver system 108. For example, for fingerprint imaging, the appropriate range gating delay after t0 can be determined by adding this waiting time to the length of time it takes for the emitted ultrasonic wave 212 to propagate from the nanoparticle 204 to the outer surface of the cover layer 102 and return to the receiver system 108.

[0064] exist Figure 2 In the illustrated example, ultrasonic waves 212 are shown as striking ridge regions 214 and valley regions 216 of the finger. There is almost no impedance contrast between ridge regions 214 and cover layer 102, so most of the energy of ultrasonic waves 212 striking ridge regions 214 is transmitted into the finger. However, there is a large impedance contrast between the air in valley regions 216 and cover layer 102, so most of the energy of ultrasonic waves 212 striking valley regions 216 is reflected.

[0065] Some of these reflected ultrasonic waves 218 are received by the ultrasonic receiver of the receiver system 108. According to some embodiments, the control system 110 can be configured to receive ultrasonic receiver signals corresponding to the ultrasonic waves 218 reflected from the target object from the ultrasonic receiver system, and perform an authentication process and / or an imaging process based at least in part on the ultrasonic receiver signals. Some ultrasonic waves can propagate directly to the ultrasonic receiver system, but these ultrasonic waves can be distinguished from the reflected ultrasonic waves by selecting a range gating delay that allows sampling of the reflected waves instead of the direct waves.

[0066] Figure 3 Another example of an apparatus configured to perform at least some of the methods disclosed herein is shown. Figure 3 The device 100 can be considered as Figure 1 Another example of apparatus 100 is shown. Figure 3 The device 100 is very similar to Figure 2 The device shown. However, in this example, the nanoparticles 204 are located in the waveguide 208. Therefore, the waveguide 208 includes the first metamaterial layer 104. The light source 206 can be configured to emit light including the resonant frequency of at least some of the nanoparticles 204. According to some examples, the control system 110 can be configured to control the light source 206 to cause the nanoparticles to emit ultrasonic waves in the range of 1 MHz to 30 MHz. According to some embodiments, the control system 110 can be configured to receive an ultrasonic receiver signal corresponding to the ultrasonic wave 218 reflected from the target object from the ultrasonic receiver system, and perform an authentication process and / or an imaging process based at least in part on the ultrasonic receiver signal.

[0067] Figure 4 is a flowchart that provides an example of a method that can be performed via some disclosed embodiments. For example, the blocks of method 400 (and blocks of at least some other disclosed methods) can be represented by Figures 1 to 3 The method 400 may be performed by the device 100 or a similar device shown in one of the embodiments. As with other methods disclosed herein, the method 400 may include more or fewer blocks than indicated. In addition, the blocks of the methods disclosed herein are not necessarily executed in the order indicated.

[0068] In this example, block 403 involves controlling the light source system to emit light that causes at least some of the nanoparticles of the first metamaterial layer to emit ultrasonic waves. Here, block 403 involves controlling the light source system to provide light pulses to the first metamaterial layer, providing pulses to cause the nanoparticles to emit ultrasonic waves in the range of 1 MHz to 30 MHz. For example, block 403 may involve the control system 110 controlling the light source system 106. Such an embodiment may cause the nanoparticles of the first metamaterial layer 104 to emit ultrasonic waves in a range suitable for an ultrasonic imaging process and / or an authentication process.

[0069] According to this example, block 405 involves receiving a first ultrasonic receiver signal from an ultrasonic receiver system corresponding to an ultrasonic wave generated by the nanoparticles and reflected from a target object. For example, block 405 may involve the control system 110 receiving the first ultrasonic receiver signal from the receiver system 108. In other examples, the first ultrasonic receiver signal may be received from a memory device (such as a buffer). The ultrasonic receiver signal may correspond to an ultrasonic wave reflected from a target object near the cover layer 102. In some examples, the target object may be a human finger, such as a user's finger. However, in other examples, the target object may be an artificial finger-like object, which may be referred to herein as a "fake finger."

[0070] In this embodiment, block 407 involves performing an imaging process and / or an authentication process based at least in part on the first ultrasound receiver signal. The data received from the receiver system 108 may be referred to herein as "image data", but the image data is typically received in the form of an electrical signal. Therefore, such image data may not necessarily be perceived by humans as an image without additional processing. In some examples, block 407 may involve a noise removal process and / or other image processing. In some examples, block 407 may involve constructing a two-dimensional image or a three-dimensional image of at least a portion of the target object.

[0071] Some disclosed embodiments may include a sensor system capable of obtaining image data from the epidermis, such as fingerprint image data and image data corresponding to sub-epidermal features. Figure 5 An example of a subcutaneous feature is shown. As used herein, the term "subcutaneous feature" may refer to any tissue layer below the epidermis 100, including the dermis, papillary layer, reticular layer, subcutaneous tissue, etc., as well as any blood vessels, lymphatic vessels, sweat glands, hair follicles, hair papillae, fat lobules, etc. that may be present in these tissue layers. Therefore, subcutaneous features may also include Figure 5 Features not shown in the figure, such as muscle tissue, bone material, etc.

[0072] If box 407 involves performing an authentication process based at least in part on the first ultrasonic receiver signal, box 407 may involve an evaluation of epidermal and / or sub-epidermal features. Some spoofing techniques are based on forming fingerprint-like features on an object, which may be a finger-shaped object. However, it would be challenging and expensive to manufacture a finger-shaped object with detailed sub-epidermal features, muscle tissue features, and / or bone tissue features. It would be even more challenging to make these features accurately correspond to the features of an authorized user. Making such features variable in a human-like bionic manner or in a manner that replicates a legitimate user raises the threshold for spoofing manufacturing. Because some of the disclosed embodiments involve obtaining attribute information based at least in part on sub-epidermal features, some such embodiments may provide more reliable authentication.

[0073] Some embodiments can perform an enrollment process and an authentication process based at least in part on sub-epidermal features. Some such processes can also be based on fingerprint image data, or on fingerprint details or fingerprint image features, such as key points derived from fingerprint image data. The authentication process can involve spoof detection and / or liveness detection.

[0074] In some examples, the user authentication process may involve comparing "attribute information" obtained from received image data based on signals from the ultrasound sensor array with stored attribute information obtained from image data that has been previously received from an authorized user during an enrollment process. According to some such examples, the attribute information may include information about sub-epidermal features, such as information about dermis features, subcutaneous tissue features, blood vessel features, lymphatic vessel features, sweat gland features, hair follicle features, hair papilla features, and / or fat lobule features, as well as minutiae or key point information associated with an enrolled fingerprint.

[0075] Alternatively or additionally, in some embodiments, the attribute information obtained from the received image data and the stored attribute information may include information about bone tissue features, muscle tissue features, and / or epidermal or subepidermal tissue features. For example, according to some embodiments, a user authentication process may involve obtaining fingerprint image data and subepidermal image data. In such an example, the authentication process may involve evaluating the attribute information obtained from the fingerprint image data.

[0076] The attribute information obtained from the received image data and the stored attribute information compared during the authentication process may include biometric template data corresponding to the received image data and biometric template data corresponding to the stored image data. One well-known biometric template data is fingerprint template data, which may indicate the type and location of fingerprint minutiae or key points. A user authentication process based on fingerprint image data attributes may involve comparing the received fingerprint template data with the stored fingerprint template data. Such a process may or may not involve directly comparing the received fingerprint image data with the stored fingerprint image data.

[0077] Similarly, the biological template data corresponding to the sub-epidermal features may include information about blood vessel attributes, such as information about the type and location of the blood vessel features (such as blood vessel size, blood vessel direction, location of blood vessel branch points, etc.). Alternatively or additionally, the biological template data corresponding to the sub-epidermal features may include attribute information about the type (e.g., size, shape, direction, etc.) and location of dermal features, subcutaneous tissue features, lymphatic vessel features, sweat gland features, hair follicle features, hair papilla features, fat lobule features, muscle tissue and / or bone material.

[0078] In some embodiments, method 400 may involve controlling a light source system to induce photoacoustic emissions from at least a portion of a target object. In some such examples, method 400 may involve receiving a second ultrasound receiver signal corresponding to an ultrasound wave generated via the photoacoustic emissions from an ultrasound receiver system. Such a method may involve performing an imaging process and / or an authentication process of block 407 based at least in part on the second ultrasound receiver signal.

[0079] According to some embodiments, method 400 may involve controlling a light source system to illuminate at least a portion of a target object. Some such embodiments may involve receiving an optical receiver signal corresponding to light reflected from the target object from an optical receiver system. For example, control system 110 may receive the optical receiver signal from an optical receiver system component of receiver system 108. According to some such examples, control system 110 may be configured to perform an imaging process or an authentication process of block 407 based at least in part on the optical receiver signal.

[0080] Figure 6 An example of a receiver system 108 including an optical receiver portion and an ultrasonic receiver portion is shown. In this example, a single layer of the receiver system 108 includes an optical receiver portion 601 and an ultrasonic receiver portion 603. As described above, some films used for screen protection can significantly attenuate ultrasonic signals. A sensor system configured to perform an authentication process and / or an imaging process based at least in part on an optical receiver signal can improve the attenuation of ultrasonic signals caused by a screen protection film.

[0081] Figure 6 The receiver system 108 shown or a similar receiver system 108 may be included in Figures 1 to 4 In any of the embodiments of the apparatus 100 shown and described above. However, Figure 6 The receiver system 108 is also included in other embodiments of the device 100, such as Fig. 7A The embodiments shown and described below.

[0082] Back to Figure 1 As can be seen, some embodiments of the device 100 may include a second metamaterial layer 114. In some examples, the second metamaterial layer 114 is configured to convert acoustic waves into light. For example, the second metamaterial layer 114 may include a plasmonic nanorod metamaterial.

[0083] In some examples, the control system 110 can be configured to receive optical receiver signals from the optical receiver system and perform an authentication process and / or an imaging process based at least in part on the optical receiver signals. At least some of the optical receiver signals can correspond to light emitted by the second metamaterial 114. However, at least some of the optical receiver signals can correspond to light reflected from the target object. According to some examples, the authentication process and / or the imaging process can also be based at least in part on the ultrasonic receiver signals.

[0084] According to some examples, control system 110 can be configured to control light source system 106 to induce photoacoustic emissions from a target object in contact with or near cover layer 102. In some examples, second metamaterial 114 can convert ultrasonic waves caused by these photoacoustic emissions into light.

[0085] Fig. 7A Another example of an apparatus configured to perform at least some of the methods disclosed herein is shown. Some embodiments of apparatus 700 may be considered to be Figure 1 Another example of the device 100 is shown. In this example, the cover layer 102 includes a metamaterial layer 714. The metamaterial layer 714 can be considered as Figure 1 An example of a second meta-material layer 114 is shown. However, some embodiments of the device 700 do not include a first meta-material layer 104 that includes nanoparticles suitable for ultrasonic penetration.

[0086] In this example, the light source system 106 does not require a waveguide. According to some examples, the light source system 106 may include one or more LEDs and / or laser diodes. In some examples, the light source system 106 may be a backlight for a display.

[0087] According to some examples, light source system 106 may be configured to induce photoacoustic emissions from a target object, such as target object 202, that is in contact with or proximate to cover layer 102. For example, control system 110 may control light source system 106 to induce photoacoustic emissions in target object 202 via light 710. In some examples, metamaterial 714 may convert ultrasonic waves 712 caused by these photoacoustic emissions into light 716, some of which may be detected by optical receivers of receiver system 108.

[0088] In some examples, the control system 110 can be configured to receive optical receiver signals from the optical receiver system and perform an authentication process and / or an imaging process based at least in part on the optical receiver signals. At least some of the optical receiver signals can correspond to light emitted by the second metamaterial 114. However, at least some of the optical receiver signals can correspond to light reflected from the target object.

[0089] In some embodiments, the receiver system 108 may also include an ultrasonic receiver system. According to some such embodiments, the optical receiver system and the ultrasonic receiver system may be located in a single layer of the receiver system 108, for example, Figure 6 As shown. In some cases, at least some of the ultrasonic waves 712 caused by the photoacoustic emission can be received by the ultrasonic receiver system. According to some examples, the authentication process and / or the imaging process can also be based at least in part on the ultrasonic receiver signal received from the ultrasonic receiver system. Some alternative embodiments can include an ultrasonic transmitter.

[0090] Such as Fig. 7A The embodiments shown and described above have potential advantages. For example, optical sensors are generally not adversely affected by screen protective films, which may degrade the performance of ultrasonic sensors. For example, the optical sensor can be placed under one millimeter thick glass (including curved 2.5D glass) and can still accurately detect fingerprints in situations where the ultrasonic fingerprint sensor can provide reduced image quality. The optical sensor may include components such as lenses to achieve a relatively large depth of focus. Therefore, the additional thickness of the screen protector can be accommodated. Because the speed of light is much greater than the speed of sound, the additional thickness of the screen protector does not significantly affect the total flight time of the optical sensor. In contrast, the additional thickness of the screen protector may cause the ultrasonic fingerprint sensor to require recalibration of the distance gating delay, and in some cases, the transmission frequency.

[0091] The receiver system 108 including both an optical receiver and an ultrasonic receiver also has advantages. The frame rate and spatial resolution of the optical and ultrasonic receivers can be adjusted. For example, the optical receiver can provide a relatively high spatial resolution at a relatively low frame rate, while the ultrasonic transceiver can provide a relatively low spatial resolution at a relatively high frame rate. One receiver can have a lower power imaging mode, and the other receiver can have a higher power imaging mode, which is used only when needed or advantageous. In some cases, the optical receiver and the ultrasonic transceiver can be tuned separately according to the characteristics of each component.

[0092] In some embodiments, the signal from the optical receiver and the signal from the ultrasonic receiver can be combined to form a single image, while in other examples, the signal from the optical receiver and the signal from the ultrasonic receiver can be used to form separate images. For example, if both the optical receiver signal and the ultrasonic receiver signal are used for an imaging process and / or an authentication process, the signal processing can involve cross-correlation of the optical receiver signal and the ultrasonic receiver signal. In some cases, image data can be obtained from the optical receiver signal or the ultrasonic receiver signal, depending on which one currently provides a higher quality signal. For example, if the image quality of the ultrasonic receiver signal is currently degraded (e.g., due to a dry finger), the optical receiver signal can be used for an imaging process and / or an authentication process.

[0093] Figure 7B Shows Fig. 7A An alternative example of layers of a device. In this example, the cover layer 102 includes two types of metamaterials. According to this embodiment, the vertical nanorods (rods) 720 are configured to convert sound waves into light waves, while the horizontal metamaterial layer 725 is configured to convert light waves into sound waves. The vertical nanorods 720 can help propagate information from a target object above the cover layer 102 to a sensor system below the cover layer 102. In some embodiments, the horizontal metamaterial layer 725 can be configured to convert light waves into sound waves. Figure 7B The vertical nanorods 720 and / or the horizontal metamaterial layer 725 may extend further through the cover layer 102 than indicated, and in some examples, may extend throughout the entire cover layer 102 .

[0094] Figure 8 Aspects of a 4×4 pixel array of sensor pixels for an ultrasound sensor system are representatively depicted. For example, each pixel 834 can be associated with a local area of ​​piezoelectric sensor material (PSM), a peak detection diode (D1), and a readout transistor (M3); many or all of these elements can be formed on or in a substrate to form a pixel circuit 836. In practice, the local area of ​​piezoelectric sensor material of each pixel 834 can convert received ultrasound energy into an electric charge. The peak detection diode D1 can register the maximum amount of charge detected by the local area of ​​piezoelectric sensor material PSM. Each row of the pixel array 835 can then be scanned, for example, by a row selection mechanism, a gate driver, or a shift register, and the readout transistor M3 of each column can be triggered to allow additional circuitry (e.g., a multiplexer and an analog-to-digital converter) to read the magnitude of the peak charge of each pixel 834. The pixel circuit 836 can include one or more TFTs to allow the gating, addressing, and resetting of the pixel 834.

[0095] Each pixel circuit 836 can provide information about a small portion of an object detected by the ultrasonic sensor system. Although for ease of illustration, Figure 8 The examples shown have a relatively coarse resolution, but ultrasonic sensors with a resolution on the order of about 500 pixels per inch or more can be configured with appropriately scaled structures. The detection area of ​​the ultrasonic sensor system can be selected based on the intended detection object. For example, the detection area can range from about 5 mm x 5 mm for a single finger to about 3 inches x 3 inches for four fingers. Smaller and larger areas, including square, rectangular, and non-rectangular geometries, can be used appropriately for target objects.

[0096] Fig.9A An example of an exploded view of an ultrasonic sensor system is shown. In this example, the ultrasonic sensor system 900a includes an ultrasonic transmitter 20 and an ultrasonic receiver 30 below a pressure plate 40. According to some embodiments, the ultrasonic receiver 30 may be Figure 1 An example of an ultrasound sensor array 102 is shown in FIG. 1 and described above. In some embodiments, the ultrasound transmitter 20 may be Figure 1 An example of an optional ultrasonic transmitter 108 as shown and described above. The ultrasonic transmitter 20 may include a substantially planar piezoelectric transmitter layer 22 and may be used as a plane wave generator. Ultrasonic waves may be generated by applying a voltage to the piezoelectric layer to expand or contract the layer (depending on the signal applied), thereby generating a plane wave. In this example, the control system 110 may generate a voltage that may be applied to the planar piezoelectric transmitter layer 22 via the first transmitter electrode 24 and the second transmitter electrode 26. In this manner, ultrasonic waves may be formed by changing the thickness of the layer via the piezoelectric effect. The ultrasonic waves may propagate through the platen 40 toward the finger (or other object to be detected). A portion of the wave that is not absorbed or transmitted by the object to be detected may be reflected, thereby returning through the platen 40 and being received by at least a portion of the ultrasonic receiver 30. The first transmitter electrode 24 and the second transmitter electrode 26 may be metallized electrodes, for example, metal layers coating opposite sides of the piezoelectric transmitter layer 22.

[0097] The ultrasound receiver 30 may include an array of sensor pixel circuits 32 and a piezoelectric receiver layer 36 disposed on a substrate 34 (which may also be referred to as a backplane). In some embodiments, each sensor pixel circuit 32 may include one or more TFT elements, electrical interconnect traces, and in some embodiments, one or more additional circuit elements, such as diodes, capacitors, etc. Each sensor pixel circuit 32 may be configured to convert an electrical charge generated in the piezoelectric receiver layer 36 proximate to the pixel circuit into an electrical signal. Each sensor pixel circuit 32 may include a pixel input electrode 38 that electrically couples the piezoelectric receiver layer 36 to the sensor pixel circuit 32.

[0098] In the illustrated embodiment, a receiver bias electrode 39 is disposed on one side of the piezoelectric receiver layer 36 near the platen 40. The receiver bias electrode 39 may be a metallized electrode and may be grounded or biased to control which signals may be passed to the array of sensor pixel circuits 32. Ultrasonic energy reflected from the exposed (top) surface of the platen 40 may be converted into localized charges by the piezoelectric receiver layer 36. These localized charges may be collected by the pixel input electrodes 38 and passed to the underlying sensor pixel circuits 32. The charges may be amplified or buffered by the sensor pixel circuits 32 and provided to the control system 110.

[0099] The control system 110 can be electrically connected (directly or indirectly) to the first transmitter electrode 24 and the second transmitter electrode 26, as well as to the receiver bias electrode 39 and the sensor pixel circuit 32 on the substrate 34. In some embodiments, the control system 110 can operate substantially as described above. For example, the control system 110 can process the amplified signal received from the sensor pixel circuit 32.

[0100] The control system 110 can control the ultrasonic transmitter 20 and / or the ultrasonic receiver 30 to obtain ultrasonic image data, for example, by obtaining a fingerprint image. Whether or not the ultrasonic sensor system 900a includes the ultrasonic transmitter 20, the control system 110 can obtain attribute information from the ultrasonic image data. In some examples, the control system 110 can control access to one or more devices based at least in part on the attribute information. The ultrasonic sensor system 900a (or an associated device) may include a memory system that includes one or more memory devices. In some embodiments, the control system 110 may include at least a portion of the memory system. The control system 110 can obtain attribute information from the ultrasonic image data and store the attribute information in the memory system. In some embodiments, the control system 110 can capture a fingerprint image, obtain attribute information from the fingerprint image, and store the attribute information obtained from the fingerprint image (which may be referred to herein as fingerprint image information) in the memory system. According to some examples, the control system 110 can capture a fingerprint image, obtain attribute information from the fingerprint image, and store the attribute information obtained from the fingerprint image, even while keeping the ultrasonic transmitter 20 in the "off" state.

[0101] In some embodiments, the control system 110 can operate the ultrasonic sensor system 900a in an ultrasonic imaging mode or a force sensing mode. In some embodiments, when the ultrasonic sensor system is operated in the force sensing mode, the control system may be able to keep the ultrasonic transmitter 20 in an "off" state. When the ultrasonic sensor system 900a is operated in the force sensing mode, the ultrasonic receiver 30 can be used as a force sensor. In some embodiments, the control system 110 can control other devices, such as a display system, a communication system, etc. In some embodiments, the control system 110 can operate the ultrasonic sensor system 900a in a capacitive imaging mode.

[0102] The pressure plate 40 can be any suitable material capable of acoustically coupling to a receiver, examples including plastic, ceramic, sapphire, metal, and glass. In some embodiments, the pressure plate 40 can be a cover plate, for example, a cover glass or lens glass for a display. In particular when using an ultrasonic transmitter 20, fingerprint detection and imaging can be performed with a relatively thick (e.g., 3 mm or thicker) pressure plate, if desired. However, for embodiments in which the ultrasonic receiver 30 is capable of imaging a fingerprint in a force detection mode or a capacitive detection mode, a thinner and relatively more compliant pressure plate 40 may be required. According to some such embodiments, the pressure plate 40 may include one or more polymers, such as one or more types of polyparaxylene, and may be significantly thinner. In some such embodiments, the pressure plate 40 may be tens of microns thick or even less than 10 microns thick.

[0103] Examples of piezoelectric materials that can be used to form the piezoelectric receiver layer 36 include piezoelectric polymers having suitable acoustic properties (e.g., an acoustic impedance between about 2.5 MRayl and 5 MRayl). Specific examples of piezoelectric materials that can be used include ferroelectric polymers such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymers. Examples of PVDF copolymers include 60:40 (molar percentage) PVDF-TrFE, 70:30 PVDF-TrFE, 80:20 PVDF-TrFE, and 90:10 PVDR-TrFE. Other examples of piezoelectric materials that can be used include polyvinylidene chloride (PVDC) homopolymers and copolymers, polytetrafluoroethylene (PTFE) homopolymers and copolymers, and diisopropylammonium bromide (DIPAB).

[0104] The thickness of each of the piezoelectric transmitter layer 22 and the piezoelectric receiver layer 36 can be selected to be suitable for generating and receiving ultrasonic waves. In one example, the PVDF planar piezoelectric transmitter layer 22 is approximately 28 μm thick and the PVDF-TrFE receiver layer 36 is approximately 12 μm thick. Example frequencies of ultrasonic waves can be in the range of 1 MHz to 30 MHz, with wavelengths on the order of millimeters or less.

[0105] Fig. 9B An exploded view of an alternative example of an ultrasound sensor system is shown. In this example, the piezoelectric receiver layer 36 has been formed into discrete components 37. Fig. 9B In the illustrated embodiment, each of the discrete components 37 corresponds to a single pixel input electrode 38 and a single sensor pixel circuit 32. However, in alternative embodiments of the ultrasound sensor system 900, there need not be a one-to-one correspondence between each of the discrete components 37, a single pixel input electrode 38, and a single sensor pixel circuit 32. For example, in some embodiments, there may be multiple pixel input electrodes 38 and sensor pixel circuits 32 for a single discrete component 37.

[0106] Fig.9A and Fig. 9B An example arrangement of an ultrasonic transmitter and a receiver in an ultrasonic sensor system is shown, wherein other arrangements are also possible. For example, in some embodiments, the ultrasonic transmitter 20 may be above the ultrasonic receiver 30 and therefore closer to the object(s) to be detected. In some embodiments, the ultrasonic transmitter may be included in an ultrasonic sensor array (e.g., a single layer of transmitters and receivers). In some embodiments, the ultrasonic sensor system may include an acoustic delay layer. For example, an acoustic delay layer may be incorporated into the ultrasonic sensor system between the ultrasonic transmitter 20 and the ultrasonic receiver 30. The acoustic delay layer may be used to adjust the timing of ultrasonic pulses and at the same time electrically insulate the ultrasonic receiver 30 from the ultrasonic transmitter 20. The acoustic delay layer may have a substantially uniform thickness, wherein the material used for the delay layer and / or the thickness of the delay layer is selected to provide a desired delay in the time at which the reflected ultrasonic energy reaches the ultrasonic receiver 30. In this way, the energy pulse carrying information about the object (due to having been reflected by the object) may arrive at the ultrasonic receiver 30 within a time range in which the energy reflected from other parts of the ultrasonic sensor system is unlikely to arrive at the ultrasonic receiver 30. In some embodiments, the substrate 34 and / or the press plate 40 may serve as an acoustic delay layer.

[0107] As used herein, a phrase referring to "at least one" of a list of items refers to any combination of those items, including single members. For example, "at least one of a, b, or c" is intended to cover: a, b, c, ab, ac, bc, and abc.

[0108] The various illustrative logics, logic blocks, modules, circuits, and algorithmic processes described in conjunction with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. The interchangeability of hardware and software has been generally described in terms of functionality and illustrated in the various illustrative components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented in hardware or software depends on the specific application and design constraints on the overall system.

[0109] The hardware and data processing apparatus for implementing the various illustrative logics, logic blocks, modules, and circuits described in conjunction with the aspects disclosed herein may be implemented or performed with a general purpose single-chip or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration. In some embodiments, specific processes and methods may be performed by circuits specific to a given function.

[0110] In one or more aspects, the functions described may be implemented by hardware, digital electronic circuitry, computer software, firmware (including the structures disclosed in this specification and their structural equivalents), or any combination thereof. Implementations of the subject matter described in this specification may also be implemented as one or more computer programs, i.e., one or more modules of computer program instructions encoded in a computer storage medium, for execution by a data processing apparatus or for controlling the operation of the data processing apparatus.

[0111] If implemented by software, these functions can be stored as one or more instructions or codes in a computer-readable medium (such as a non-transitory medium) or sent through a computer-readable medium. The process of the method or algorithm disclosed herein can be implemented in a processor-executable software module, which can be located in a computer-readable medium. Computer-readable media include computer storage media and communication media, and communication media include any medium capable of transmitting a computer program from one place to another. The storage medium can be any available medium that can be accessed by a computer. As an example and not limitation, non-transitory media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage devices, or any other medium that can be used to store the desired program code in the form of an instruction or data structure and can be accessed by a computer. In addition, any connection can be properly referred to as a computer-readable medium. As used herein, the disk and disc include compact disks (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks and blue-ray discs, wherein the disks usually reproduce data magnetically, and the discs reproduce data optically with lasers. The above combination should also be included in the scope of computer-readable media. Additionally, the operations of a method or algorithm may be embodied as one or any combination or set of codes and instructions in a machine-readable medium and a computer-readable medium, which may be incorporated into a computer program product.

[0112] Various modifications to the embodiments described in this disclosure will be apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other embodiments without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the embodiments shown herein, but rather to the widest scope consistent with the claims, principles, and novel features disclosed herein. The word "exemplary" is used specifically herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0113] Certain features described in this specification in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable subcombination. In addition, although features may be described above as functioning in certain combinations, and even initially claimed as such, in some cases, one or more features from a claimed combination may be deleted from the combination, and a claimed combination may be directed to a subcombination or a variation of a subcombination.

[0114] Similarly, although operations are depicted in a particular order in the accompanying drawings, this should not be understood as requiring such operations to be performed in the particular order or sequence shown, or requiring that all operations shown be performed to obtain the desired results. In some cases, multitasking and parallel processing can be advantageous. In addition, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated in a single software product or encapsulated in multiple software products. Additionally, other embodiments are also within the scope of the following claims. In some cases, the actions listed in the claims can be performed in different orders, and the desired results can still be obtained.

[0115] It should be understood that unless the features in any specific embodiment described are explicitly identified as incompatible with each other, or the surrounding context implies that they are mutually exclusive and not easily combined in a complementary and / or supporting sense, the overall concept and envision of the present disclosure contemplates that the specific features of these complementary embodiments can be selectively combined to provide one or more comprehensive but slightly different technical solutions. Therefore, it will be further understood that the above description is given only as an example, and detailed modifications may be made within the scope of the present disclosure.

Claims

1. A fingerprint sensing device, comprising: Covering layer; a first metamaterial layer within or proximate to the cover layer, the first metamaterial comprising nanoparticles configured to resonate and generate ultrasonic waves when illuminated by light; a light source system configured to provide light to the first metamaterial layer; as well as The receiver system includes an ultrasonic receiver system configured to receive ultrasonic waves reflected from a target object in contact with or close to a surface of the cover layer.

2. The fingerprint sensor device according to claim 1, wherein: The light source system includes a waveguide proximate to the first metamaterial layer, the waveguide configured to receive light from the light source and provide the light to the first metamaterial layer.

3. The fingerprint sensor device according to claim 1, wherein: The light source system includes a light source configured to emit light including a resonant frequency of at least some of the nanoparticles.

4. The fingerprint sensing device according to claim 1, further comprising a control system, wherein the control system is configured to control the light source system so that the nanoparticles emit ultrasonic waves in the range of 1 MHz to 30 MHz.

5. The fingerprint sensor device according to claim 4, wherein: The control system is configured to: receiving, from the ultrasonic receiver system, an ultrasonic receiver signal corresponding to ultrasonic waves reflected from the target object; and At least one of an authentication process or an imaging process based at least in part on the ultrasound receiver signal is performed.

6. The fingerprint sensor device according to claim 1, wherein: The cover layer includes an optically opaque pressboard or an optically translucent pressboard.

7. The fingerprint sensor device according to claim 1, wherein: The cover layer is optically transparent.

8. The fingerprint sensor device according to claim 7, wherein: The receiver system comprises an optical receiver system.

9. The fingerprint sensor device according to claim 8, wherein: The single layer of the receiver system includes a portion of the optical receiver system and a portion of the ultrasound receiver system.

10. The fingerprint sensing device of claim 8, further comprising a second metamaterial layer configured to convert acoustic waves into light.

11. The fingerprint sensing device according to claim 10, further comprising a control system, wherein the control system is configured to control the light source system, wherein: The control system is also configured to: receiving an optical receiver signal from the optical receiver system; as well as At least one of an authentication process or an imaging process based at least in part on the light receiver signal is performed.

12. The fingerprint sensing device according to claim 11, wherein: At least some of the light receiver signals correspond to light emitted by the second metamaterial.

13. The fingerprint sensing device according to claim 11, wherein: The control system is configured to control the light source system to induce photoacoustic emissions from the target object.

14. The fingerprint sensing device according to claim 11, wherein: At least some of the light receiver signals correspond to light reflected from the target object.

15. The fingerprint sensing device according to claim 11, wherein: The control system is also configured to: receiving, from the ultrasonic receiver system, an ultrasonic receiver signal corresponding to ultrasonic waves reflected from the target object; and An authentication process or an imaging process is performed based at least in part on the ultrasound receiver signal.

16. The fingerprint sensing device according to claim 10, wherein: The cover layer includes the second metamaterial layer.

17. The fingerprint sensing device according to claim 1, wherein: The ultrasound receiver system includes a piezoelectric layer including at least one of microparticles or nanoparticles in a piezoelectric polymer matrix.

18. The fingerprint sensing device according to claim 17, wherein: At least one of the microparticles or nanoparticles includes a ferroelectric material.

19. A mobile device comprising the fingerprint sensing device according to claim 1.

20. The mobile device according to claim 19, wherein: The mobile device comprises a cellular telephone.

21. A method for fingerprint sensing, comprising: Controlling the light source system to emit light, wherein the light causes at least some of the nanoparticles in the first metamaterial layer to emit ultrasonic waves; receiving, from an ultrasonic receiver system, a first ultrasonic receiver signal corresponding to ultrasonic waves generated by the nanoparticles and reflected from a target object; and At least one of an imaging process or an authentication process is performed based at least in part on the first ultrasound receiver signal.

22. The method according to claim 21, further comprising: controlling the light source system to illuminate at least a portion of the target object; receiving, from an optical receiver system, an optical receiver signal corresponding to light reflected from the target object; as well as The imaging process or the authentication process is performed based at least in part on the optical receiver signal.

23. The method according to claim 21, further comprising: controlling the light source system to induce photoacoustic emission from at least a portion of the target object; receiving from the ultrasound receiver system a second ultrasound receiver signal corresponding to the ultrasound wave generated via the photoacoustic emission; and At least one of the imaging process or the authentication process is performed based at least in part on the second ultrasound receiver signal.

24. One or more non-transitory storage media storing instructions for controlling one or more devices to perform a method, the method comprising: Controlling the light source system to emit light, wherein the light causes at least some of the nanoparticles in the first metamaterial layer to emit ultrasonic waves; receiving, from an ultrasonic receiver system, a first ultrasonic receiver signal corresponding to ultrasonic waves generated by the nanoparticles and reflected from a target object; and At least one of an imaging process or an authentication process is performed based at least in part on the first ultrasound receiver signal.

25. One or more non-transitory storage media according to claim 24, wherein: The method further comprises: controlling the light source system to illuminate at least a portion of the target object; receiving, from an optical receiver system, an optical receiver signal corresponding to light reflected from the target object; and The imaging process or the authentication process is performed based at least in part on the optical receiver signal.

26. One or more non-transitory storage media according to claim 24, wherein: The method further comprises: controlling the light source system to induce photoacoustic emission from at least a portion of the target object; receiving from an ultrasonic receiver system a second ultrasonic receiver signal corresponding to an ultrasonic wave corresponding to the photoacoustic emission; and At least one of the imaging process or the authentication process is performed based at least in part on the second ultrasound receiver signal.

27. A fingerprint sensing device, comprising: Covering layer; a first metamaterial layer within or proximate to the cover layer, the first metamaterial comprising nanoparticles configured to resonate and generate ultrasonic waves when illuminated by light; a light source component for providing light to the first metamaterial layer; as well as The receiver system includes an ultrasonic receiver system configured to receive ultrasonic waves reflected from a target object in contact with the surface of the cover layer.

28. The fingerprint sensing device according to claim 27, wherein: The light source component includes a waveguide proximate to the first metamaterial layer, the waveguide configured to receive light from the light source and provide the light to the first metamaterial layer.

29. The fingerprint sensing device according to claim 27, wherein: The light source component includes a light source configured to emit light including a resonant frequency of at least some of the nanoparticles.

30. The fingerprint sensing device according to claim 27, further comprising a control component for controlling the light source system to emit light pulses in the range of 1 MHz to 30 MHz at time intervals.

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