The investigation of the pressure sensor chip’s design developed for operation in ultralow differential pressure ranges has been conducted. The optimum geometry of a diaphragm has been defined using available technological resources. The pressure sensor chip with an area of $6.15\times6.15$ mm has an average sensitivity S of 34.5 mV/ $\kappa $ Pa/V at nonlinearity 2K $_{NL} =0.81$ %FS and thermal hysteresis up to 0.6 %FS was created. Owing to the chip connection with stop elements, the burst pressure reaches $450~\kappa $ Pa. The developed pressure sensor can be used in medicine, automotive industry and highly specialized scientific developments.