Abstarct: Cardiovascular diseases are recognized as one of the leading causes of mortality worldwide, and the management of heart rhythm in affected patients is of vital importance. Cardiac pacemakers are essential medical devices that regulate and maintain a steady heartbeat. Their proper function requires a continuous and stable energy supply; therefore, the batteries used in these devices must provide a long lifespan and high energy density in order to minimize the need for frequent replacement and ensure patient safety. Nuclear betavoltaic converters, with the ability to deliver stable energy over extended periods, represent a promising option for powering pacemakers. In this study, a radioactive nickel-63 source, with a half-life of about 100 years and low β-emission energy, was employed. Owing to its stability and safety, this isotope offers the potential for long-term energy supply. The semiconductors used were silicon carbide (SiC) and titanium dioxide (TiO₂). SiC was selected due to its high resistance to heat and radiation, while TiO₂ was chosen for its suitable band gap and favorable optical properties. These semiconductors play a key role in converting the radiative energy of the source into electrical energy. To determine the optimal laxyer thicknesses, numerical simulations were performed using the MCNPX code. In 36 simulation runs, the thicknesses of SiC and TiO₂ laxyers were gradually increased to identify the ideal thickness that maximizes stored energy within the battery. Additionally, the stored energy and associated error percentage for each laxyer were calculated. baxsed on these data, the open-circuit voltage, short-circuit current, fill factor, battery efficiency, and their corresponding errors were thoroughly evaluated. According to the performance assessment, the SiC-baxsed betavoltaic battery exhibited higher open-circuit voltage and efficiency compared to the TiO₂-baxsed design. In line with previous studies on SiC, experimental fabrication was continued using this material, while TiO₂ was employed solely in simulations for comparison. Initially, the doctor blade method was selected for film deposition due to its economic feasibility and simplicity in achieving the desired thickness. However, fine cracks were observed in all five fabricated samples. Consequently, sputtering was employed in the next stage, enabling the successful deposition of high-quality SiC semiconductor laxyers on the chosen substrates. The fabricated samples were characterized using FESEM to examine the precise laxyer thickness and surface morphology, ensuring coating quality. Hall effect measurements confirmed the N-type conductivity of the SiC semiconductor and provided further insights into its electrical properties. For the top electrode, gold was deposited via sputtering. Following preparation, the samples underwent UV-Vis and I-V measurements to evaluate their optical and electrical properties. The obtained results provide comprehensive insights into the performance of betavoltaic batteries and offer valuable guidelines for the optimal design of cardiac pacemakers with enhanced efficiency and extended operational lifetime. In the testing phase, a substitute source for Strontium-90 was used. The simulation section was repeated using this alternative source, and the results obtained from this simulation were compared with those from the fabricated component.