The work presented is done at CERN and at the University of Geneva on the ATLAS ITk framework. HV-CMOS sensors are being investigated and characterised to be used in CCPDs (Capacitively Coupled Pixel Detectors). CCPDs are possible due to the possibility of the application of high voltage on the substrate of CMOS chips. This depletes the substrate of the chip, making it sensitive to particle interactions. The CMOS chip amplifies the signal generated by the particle and makes it possible to capacitively transfer the signal, through a layer of glue, to the read out ASIC. This avoids the use of bump bonds, making cheaper to build larger pixel detectors. The work presented involves TCAD simulations of the sensor chip design with TCT measurements on real devices. At the university's clean room, the sensor wafer is probed in order to use good sensors in the assembly with the FE-I4 read out ASIC. The flip-chip is done at the University of Geneva as well and pattern recognition is used to precisely align the chips together. A FPGA-based read out system was developed for the CCPD assemblies. Laboratory measurements, such as DAC scans and test pulse calibration, are performed with controlled environment. Finally, multiple test beam campaigns are done, gradually increasing the irradiation dose on the devices under test, in order to measure the performance of the chip, and results are presented from beam tests at CERN SPS (2016) and Fermilab (2017).