Measuring the flow rate of gases and liquids non-intrusively, without introducing in-line components, is a challenge faced by a variety of different industrial and commercial processes. One technology with the potential to address this issue is the thermal mass flow meter. These meters act by measuring the ability of a flowing fluid to transfer heat away from a heating element. Externally mounted heating elements have traditionally been difficult to implement, requiring long sections of pipe to equilibrate the temperature of the fluid with the temperature of the pipe. Researchers at the Princeton Plasma Physics Laboratory have invented a new method to address this challenge. Rather than measure the ability of the fluid to transfer heat from an element to an upstream or downstream temperature sensor, the system measures the power required to maintain set temperatures at two locations. This bipolar configuration allows the user to obtain an accurate flow measurement regardless of fluid temperature fluctuation.