This study develops a piezoresistive low pressure sensor which sensing range is defined below to 1psi. The sensing range of this target is in the range of human breath. Thus, the application lies in the medical instrument and monitoring systems. The low pressure sensor can detect the amplitude and frequency of the breath to monitor and record the breathing conditions of patients or elders for analyzing or emergency requests. In order to find out the significant structure factors for device performance and fabrication yield, this study builds complete platform from design, fabrication to testing. In summary, this study tries to promote the device performance, such as sensitivity and linearity, to a high specification of product.