Photonics plays a key role in many applications, such as a detection of environmental or toxic gases, analyses of food or health-related products. Those applications depend on the development of highly advanced photonic components working in the mid-infrared (MIR) wavelength range. These components have always been difficult and expensive to make, as they are not compatible with standard microelectronic or photonic fabrication processes. LASTSTEP ambitions to address this issue by developing the world-first all-Group-IV photonic platform using silicon-germanium-tin alloys (SiGeSn). Focusing on the MIR 2-5 m region essential for sensing of chemical species, the project aims to ensure a wide scale adoption of the developed technology by offering a fully monolithic solution compatible with standard state-of-the-art 200mm CMOS manufacturing processes. The approach will enable cost-effective solutions for sensing, but also for autonomous navigation or consumer products. To achieve this objective, LASTSTEP gathers a world class consortium composed of 3 academic partners, 2 RTOs and 3 industrials. The partners are: -leaders of a CMOS compatible technology for growth and processing of GeSn direct bandgap alloys in an industry-relevant environment - two SMEs well-established on the markets of gas and liquid sensing - world leading PIC design and test-house company to ensure further exploitation of results. LASTSTEP will develop four prototypes based on the fully-group-IV photonic platform for two use-cases. Prototypes will first be assembled from discrete components, then integrated on PICs. LASTSTEP aims to secure for Europe an outstanding position in development and economic exploitation of Si photonics, thereby anticipating maximal return on investment for the EU society. LASTSTEP will bring the decisive further development of Si photonics into a technologically mature MIR platform ready for innovations in the communications, sensing, health, food and safety sector.