A sensing device includes a micro-electromechanical sensor, a source follower and an amplifier. The source follower includes a first output module including a first transistor and a second transistor. The micro-electromechanical sensor is configured to generate an input signal. A first terminal of the first transistor is configured to receive a first reference voltage. A second terminal and a control of the first transistor are electrically connected to the first output terminal and to a first current source respectively. A first terminal and a second terminal of the second transistor are electrically connected to the second terminal and the control terminal of the first transistor respectively. A control terminal of the second transistor is configured to receive the input signal. A first input terminal and a second input terminal of the amplifier are electrically connected to a first output terminal configured to receive a common-mode voltage respectively.