With respect to heat supply, different methods have been employed. Almassian et al. give a comprehensive overview of different possible heating methods in their review paper [12]. Not all of the mentioned methods are easy to implement in low-cost and portable lab-on-a-chip devices due to their bulkiness or implementation costs. Examples of these rather difficult methods are using heating via induction, infrared, or microwave radiation. Others are not useful due ot their challenging temperature control, like with heating up the system using exothermic reactions. Within the field of DNA amplification, different mechanisms of amplification exist. Some are based on thermo cycling processes, e.g., PCR, whereas others are isothermal. The use of an isothermal amplification technique puts less requirements on the heaters. Isothermal processes are either truly isothermal or consisting of three different temperatures, as they have a thermal denaturation step before and a termination step after the elongation step. The switching between these temperature steps does not have to be as fast as with thermal cycling steps in, for example, PCR amplification reactions. The use of less temperature variations makes it easier to maintain the set temperature as there is less heating an cooling involved. Furthermore, it eliminates the use of a continuous flow approach in systems with low thermal conductivities, e.g., polymers. Therefore, it is easier to implement within lab-on-a-chip devices [17,21]. Isothermal DNA amplification reactions can already be performed by putting the chip on a commercially available hotplate [22,23] or Peltier elements [24,25]. However, these heating systems are bulky and power-consuming. Therefore, they are not useful for portable equipment or operation at remote locations. Miniaturizing heaters lowers the bulkiness and power consumption. Miniaturized heaters can be integrated as integrated resistive heaters, e.g., as deposited thin-film metal [26,27,28,29] or as laminated Cu foil [30], or as micro-Peltier elements [31,32]. These miniaturized heaters can be implemented directly onto the microfluidic chip [28] or on a different substrate and leter incorporated onto the microfluidic chip [33,34,35,36]. The geometry of such a heater contributes significantly to the uniformity of the heat distribution within the chip [26,37]. One method to accurately control the temperature is the use of a proportional-integral-derivative (PID) controlled thermostat. These PID controllers are coupled to the electrical heaters and use a thermocouple as feedback-loop to the controller [22,23,24,25].