The overarching goal of Engineered Heart Tissues (EHTs) is to develop functional 3D heart tissues in vitro with the potential to find drug targets, identify drug toxicity and predict the effects of the drugs in the body. This 3D model of the cardiac tissue consists of a bunch of cells, self-assembled around specific anchoring points the main aim of which is to support tissue formation. Although this model is very promising, still has to overcome an important drawback which is the lack of maturation of iPSC-derived cardiomyocytes (CM). This obstacle leads to limited recreation of the adult human cardiac tissue physiology. It has been shown that electrical stimulation of cardiac cells is one of the most important factors for cardiomyocyte’s maturation. Therefore, the principal goal of this thesis is to design and fabricate an electrical stimulator device and integrated electrodes in an existing EHT platform for electrical stimulation of cardiomyocytes. In the beginning, a literature study was conducted on different electrical stimulation methods and existing electrical stimulation devices for this purpose. For the first part of the thesis which was the design and fabrication of electrical stimulator, the electrical stimulation parameters that must be fulfilled by this device, were specified. Various hardware design approaches were studied in detail and compared before the design and implementation of the final idea. Simulations of the selected method using the LTSpice software tool were performed in order to study the behavior of the electrical stimulator design. The device is a 16-channel electrical stimulator that provides perfect rectangular biphasic pulses in the range of±15Vwith adjustable voltage amplitude, frequency and duty cycle. A user-friendly interface allows the user to select the desired channel of stimulation and the signal is distributed providing electrical stimulation to a total of EHT platforms. Therefore, this device was designed in a way to be connected with a second Printed Circuit Board(PCB) which hosts 16-EHT with integrated electrode chips. The 16-EHT holder (PCB)was also designed to suit in a 96-well plate, used by biologists for cardiac-cell culturing inside the incubator. The characterization of the electrical stimulator took place in the measurement room of the EKL lab. The results of the measurements verify the precision and efficiency of the electrical stimulator circuit as they are in excellent agreement with the simulations. The second part of the thesis includes the fabrication of integrated electrode-chips. The fabrication was conducted at EKL lab, in the Microelectronics Department of TUD using clean room microfabrication techniques. The selected electrode material was TiN due to its unique mechanical properties and the electrodes were fabricated on PDMS, encapsulated between two layers of polyimide. The main steps required for the integration of these electrodes in the existing EHT platform have been also carried out.