Improving the resolution of MEMS sensors always means increasing the cost of the component (surface area) or his electronics (complexity and power consumption). In view of the current challenges of energy sobriety, it is essential to explore new disruptive ways to reduce the impact of high-performance sensors. Chaos is a deterministic phenomenon exponentially sensitive to small variations. Little studied until recently, it can be simply implemented in the dynamics of MEMS sensors, to amplify weak signals and increase resolution. Ultimately, this is an "in-sensor computing" method, making it possible to do away with some of the measurement electronics. The aim of this thesis is to create the first MEMS demonstrator for in-sensor computing in the chaotic regime. To achieve this, we propose to study, through in-depth characterization/modeling work, this new operating regime on MEMS sensors already available at DCOS/LICA (M&NEMS and MUT beams). These first steps in understanding the link between measurand and MEMS response in the chaotic regime will enable us to move on to other applications, notably in the field of cryptography.