Recently, a new design of micromachined thermal accelerometers was the subject of new studies since they differ from all the other types of accelerometers by the absence of seismic mass and can provide a shock survival up to 50000 g. In this paper, we present the elements of theory which are necessary for the comprehension of the sensor principle and its design optimisation. Manufacturing stages and experimental results are also presented and the performances of the different sensors described in the literature are compared.