Abstract: An electronic device may include one or more ultrasonic temperature sensors. The ultrasonic temperature sensors may be formed in openings or cavities in a housing of the electronic device. The ultrasonic temperature sensors may include ultrasonic transmitters that transmit signals at different ultrasonic frequencies and ultrasonic receivers that receive the transmitted signals. Phase differences between the received ultrasonic signals may be used to determine the speed of sound of ambient air and therefore calculate the temperature of the ambient air. The ultrasonic transmitters and receivers may include piezoelectric micromachined ultrasound transducers (PMUTs). Each transmitter and receiver may be a dedicated transmitter or receiver, or may transmit and receive ultrasonic signals. Each receiver may include an array of PMUTs that receive ultrasonic signals of different frequencies. The PMUTS may be formed on complementary metal-oxide semiconductors (CMOS).

Abstract: Devices for ultrasonic transmission and/or reception having a piezoelectric micromachined ultrasonic transducer (pMUT). The device employs a material such as lithium niobate as a piezoelectric layer in a membrane suspended over a cavity. Two activation electrodes on an upper surface of the membrane can activate one or more flexural modes of mechanical vibration in the membrane, the flexural modes of vibration including a displacement in a cross-sectional plane of the membrane. The device can be used individually or in an array. The device can be configured for use in a liquid medium or in biological tissue. A method of operating an ultrasonic transducer is provided. A method of fabrication of an ultrasonic transducer is provided.

Abstract: Implantable bio-heating and intrabody communication systems use arrays of piezoelectric micromachined ultrasonic transducers (pMUTs) to provide ultrasound-based diagnosis and treatment of medical conditions. Systems involving one or more pMUT arrays can be implanted into the body or integrating into smart ingestible pills to enable monitoring of a medical condition and/or continuous or intermittent application of hyperthermia and other treatments.