Abstract: Systems and techniques are described herein for user identification. For instance, a technique can include receiving at least one biosignal from a sensor, the at least one biosignal indicative of a blood perfusion of a user. The technique can further include extracting at least one feature from the at least one biosignal, comparing the extracted at least one feature to at least one template feature associated with an enrolled user, determining, based on comparing the extracted at least one feature to the at least one template feature, whether the user matches the enrolled user, and outputting an indication of whether the user matches the enrolled user.

Abstract: In some aspects, a user device may initiate a biometric measurement operation relating to a user of the user device. The user device may monitor, using a pressure sensor of the user device, whether a pressure at an interface between a body of the user and the user device is within a range used for obtaining data for a biometric measurement. The user device may provide an indication of whether the user is to adjust the pressure based on whether the pressure is within the range. The user device may obtain the data for the biometric measurement. Numerous other aspects are described.

Abstract: The described techniques support a sensing scheme for electromagnetic excitation in ultrasonic imaging sensors. A biological tissue may be sensed and imaged using an electromagnetic excitation process to generate ultrasonic waves, such as, within the tissue. A component of a device may generate one or more pulses of electromagnetic waves, which may encounter and enter the biological tissue. The electromagnetic waves may excite the biological tissue and generate ultrasonic waves via expansion and contraction of the tissue upon heating. The ultrasonic waves may propagate within the biological tissue and may be sensed by an ultrasonic receiver array. The ultrasonic waves may be converted to pixel image data of a biometric image and may be used for biometric authentication. This process may be repeated to reconstruct an image of the finger at multiple plane slices of the finger.

Abstract: Some disclosed methods involve controlling, via a control system, a light source system to emit a plurality of light pulses into biological tissue at a pulse repetition frequency, the biological tissue including blood and blood vessels at depths within the biological tissue. Such methods may involve receiving, by the control system, signals from the piezoelectric receiver corresponding to acoustic waves emitted from portions of the biological tissue, the acoustic waves corresponding to photoacoustic emissions from the blood and the blood vessels caused by the plurality of light pulses. Such methods may involve detecting, by the control system, heart rate waveforms in the signals, determining, by the control system, a first subset of detected heart rate waveforms corresponding to vein heart rate waveforms and determining, by the control system, a second subset of detected heart rate waveforms corresponding to artery heart rate waveforms.

Abstract: An apparatus may include a cover layer, a layer of first metamaterial proximate (or in) the cover layer, a light source system configured for providing light to the layer of first metamaterial and a receiver system. The first metamaterial may include nanoparticles configured to create ultrasonic waves when illuminated by light. The receiver system may include an ultrasonic receiver system configured to receive ultrasonic waves reflected from a target object in contact with, or proximate, a surface of the cover layer. The control system may be configured to receive ultrasonic receiver signals from the ultrasonic receiver system corresponding to the ultrasonic waves reflected from the target object and to perform an authentication process and/or an imaging process that is based, at least in part, on the ultrasonic receiver signals.

Abstract: An apparatus may include a cover layer, a layer of first metamaterial proximate (or in) the cover layer, a light source system configured for providing light to the layer of first metamaterial and a receiver system. The first metamaterial may include nanoparticles configured to create ultrasonic waves when illuminated by light. The receiver system may include an ultrasonic receiver system configured to receive ultrasonic waves reflected from a target object in contact with, or proximate, a surface of the cover layer. The control system may be configured to receive ultrasonic receiver signals from the ultrasonic receiver system corresponding to the ultrasonic waves reflected from the target object and to perform an authentication process and/or an imaging process that is based, at least in part, on the ultrasonic receiver signals.

Abstract: The described techniques support a sensing scheme for electromagnetic excitation in ultrasonic imaging sensors. A biological tissue may be sensed and imaged using an electromagnetic excitation process to generate ultrasonic waves, such as, within the tissue. A component of a device may generate one or more pulses of electromagnetic waves, which may encounter and enter the biological tissue. In some examples, the component may be a display interface or may be different from a display interface of the device. The electromagnetic waves may excite the biological tissue and generate ultrasonic waves via expansion and contraction of the tissue upon heating. The ultrasonic waves may propagate within the biological tissue and may be sensed by an ultrasonic receiver array. The sensed ultrasonic waves may be converted to pixel image data of a biometric image and may be used for biometric authentication.

Abstract: The described techniques support a sensing scheme for electromagnetic excitation in ultrasonic imaging sensors. A biological tissue may be sensed and imaged using an electromagnetic excitation process to generate ultrasonic waves, such as, within the tissue. A component of a device may generate one or more pulses of electromagnetic waves, which may encounter and enter the biological tissue. In some examples, the component may be a display interface or may be different from a display interface of the device. The electromagnetic waves may excite the biological tissue and generate ultrasonic waves via expansion and contraction of the tissue upon heating. The ultrasonic waves may propagate within the biological tissue and may be sensed by an ultrasonic receiver array. The sensed ultrasonic waves may be converted to pixel image data of a biometric image and may be used for biometric authentication.

Abstract: The described techniques support a sensing scheme for electromagnetic excitation in ultrasonic imaging sensors. A biological tissue may be sensed and imaged using an electromagnetic excitation process to generate ultrasonic waves, such as, within the tissue. A component of a device may generate one or more pulses of electromagnetic waves, which may encounter and enter the biological tissue. The electromagnetic waves may excite the biological tissue and generate ultrasonic waves via expansion and contraction of the tissue upon heating. The ultrasonic waves may propagate within the biological tissue and may be sensed by an ultrasonic receiver array. The ultrasonic waves may be converted to pixel image data of a biometric image and may be used for biometric authentication. This process may be repeated to reconstruct an image of the finger at multiple plane slices of the finger.