This paper reports the development of a novel device with an ultra-thin gap filled with nanofluid in between two parallel metallic electrodes, which will allow, for the first time, practical applicable, affordable, and mass-producible direct thermoelectric energy generation at room temperature. Compared to the state of the art, the power density of our device exceeds conventional thermionic energy generators by orders of magnitude and may offer close to uW power in a volume of 1cm 3 thus making it attractive for IoT, wearable electronics and other standalone applications. In addition, our device is compatible with roll-to-roll and flexible glass processes for low-cost and large area production.