There is provided a device (100) comprising an inner member (102) configured to be worn around a finger (104) of a subject and an outer member (106) positioned in a spatial arrangement with respect to the inner member (102). The device (100) comprises at least one light source (108) arranged on the inner member (102) and/or the outer member (106), which is configured to emit light (112) to illuminate the finger (104). The device (100) comprises at least one light detector (110) arranged on the inner member (102) and/or the outer member (106), which is configured to obtain optical signals from the finger (104). The inner member (102) is movable relative to the outer member (106) to enable the at least one light detector (110) to obtain optical signals for different light paths through the finger (104) for use in measuring blood pressure.
