Aspects of the technology described herein relate to an apparatus including an ultrasound-on-a-chip device configured to be bound to a user's wrist. The ultrasound-on-a- chip device may include a two-dimensional array of ultrasonic transducers. The transducers may be capacitive micromachined ultrasonic transducers (CMUTs) and may be configured to emit ultrasound waves having a frequency between approximately 5-20 MHz. A coupling strip may be coupled to the ultrasound-on-a-chip device to reduce the air gap between the ultrasound-on-a-chip device and the user's wrist. The ultrasound-on-a-chip device may be waterproof and may be able to perform both transverse and longitudinal ultrasound scanning without being rotated. The ultrasound-on-a-chip device may be configured to calculate pulse wave velocity through a blood vessel in a user's wrist.本文中所描述的技術之態樣係關於一種包括經組態以戴至一使用者之手腕的一超音波晶片裝置之設備。該超音波晶片裝置可包括超聲波轉換器之一二維陣列。所述轉換器可為電容式微機械超聲波轉換器（CMUT），且可經組態以發出具有在大約5 MHz至20 MHz之間的一頻率的超音波。一耦接條帶可耦接至該超音波晶片裝置以減少該超音波晶片裝置與該使用者之手腕之間的氣隙。該超音波晶片裝置可防水，且可能夠在不旋轉的情況下執行橫向及縱向超音波掃描兩者。該超音波晶片裝置可經組態以計算穿過一使用者之手腕中之一血管的脈衝波速度。
