Abstract: A finger-worn sensing device includes a measurement-device body and a finger-worn structure. The finger-worn structure includes a carrying base on which the measurement-device body can be detachably mounted. The finger-worn structure also includes a first elastic band and a second elastic band, which extend from opposite sides of the carrying base and which overlap each other under the carrying base to form an annular space for the user's finger. The first elastic band has a first free end. The second elastic band has a second free end. The first free end is closer to the annular space than the second free end. A light emitter and a light receiver are located on the inner walls of the first and second elastic bands, respectively. The light emitter and the light receiver are arranged opposite each other so that they can optically sense physiological readings from the finger.