Abstract: Methods, apparatus, and systems for calibration of counterpressures using a force sensor and/or estimation of a physiological parameter of a user (such as blood pressure) are disclosed. In some embodiments, a user device may include: a signal source system; a sensor system; an interface portion; a force sensor system, the force sensor system configured to measure an external pressure applied to the interface portion during contact by the user; and a control system configured to: obtain calibration data correlating one or more external pressure values to one or more calibration factor values; determine, using the calibration data, a calibration factor based on the external pressure applied to the interface portion during the contact by the user; and estimate a physiological parameter based on the calibration factor, and one or more physical characteristics of the target object of the user determined based on the signals detected by the sensor system.

Abstract: Devices and systems for controlling pressure during sensing are disclosed. Such sensors and/or systems may be embodied in a wearable user device. The wearable user device may include a cuff configured to apply a pressure to a portion of a user at a plurality of discrete pressure levels over a plurality of time periods; a biometric sensor configured to obtain a plurality of sensor measurements associated with a blood vessel of the user at corresponding ones of the plurality of discrete pressure levels during corresponding ones of the plurality of time periods; and a wearable structure including the cuff and the biometric sensor.

Abstract: Devices and systems for controlling pressure during sensing are disclosed. Such sensors and/or systems may be embodied in a wearable user device. The wearable user device may include a cuff configured to apply a pressure to a portion of a user at a plurality of discrete pressure levels over a plurality of time periods; a biometric sensor configured to obtain a plurality of sensor measurements associated with a blood vessel of the user at corresponding ones of the plurality of discrete pressure levels during corresponding ones of the plurality of time periods; and a wearable structure including the cuff and the biometric sensor.