AFM-IR is a hybrid technique combining atomic force microscopy and mid-infrared spectroscopy. The working principle is based on a local, short-lived photo-thermal absorption of infrared light induced by a pulsed, tunable EC-QCL source. This excitation then is measured by the cantilever probe and the oscillation amplitude is directly proportional to the absorption and thus an absorption spectrum is generated. Experiments in liquids require a bottom-illuminated setup due to the reduced sensitivity in liquids such as water, thus in conventional measurements an IR transparent prism (e.g. zinc selenide;) is used, where the ingoing beam undergoes a total internal reflection, and the developed evanescent field is localized on the crystal face, where the sample sits. Nevertheless, these prisms come with limitations. Handling, sample preparation and functionalization on ZnSe prisms is not easy. Last but not least, the cost of an ATR prism is not insignificant. Our method for AFM-IR measurements in liquid introduces a novel sample carrier, a flat silicon-based ATR crystal. The flat shape allows easy handling and spin coating of samples on the carrier. As the carrier ATR is made of silicon, surface functionalization is very easy, and one can refer to a vast amount of literature. Rapid prototyping allowed to redesign the sample carrier-holder. We also had to consider, that the IR beam takes a different path in the prism, than in air, because of the shape of the ATR. We have proven, that our novel approach and method allows performing cost-effective, functionalizable measurements on the nanoscale in liquids.