An apparatus includes a device including a pair of electrodes and a channel producing an electro-osmotic flow or electrophoretic flow of a liquid by applying a voltage between the pair of electrodes, and an impedance connected to the pair of electrodes, wherein a voltage resulting from thermal noise is applied to the pair of electrodes by giving a temperature difference between the channel and the impedance, and thermal energy corresponding to the temperature difference is converted into a flow of the liquid, the flow of the liquid being mechanical energy.