technical note: a low cost pressure sensor for long-term uterine contraction monitoring

home uterine activity monitoring (huam) has demonstrated to be of great value for preventing preterm labor in recent years. in this research, a low cost monitoring device for non-invasive monitoring of the uterine activity in pregnant women is presented. the new device has been designed based on an inductive colpitz oscillator and vertical displacement of a ferrite core in a coil. the resulting frequency of the oscillator is proportional to the pressure in the external surface of the abdomen. this frequency is measured by the portable monitor. a low-power static random access memory (sram) provides long-term data storage. the proposed sensor for detecting uterine contractions has light weight, high stability and low cost. this sensor is very simple to manufacture and use for long-term ambulatory monitoring of the uterine activity. furthermore, this sensor can be calibrated using software. other features of the sensor are, resolution of 0.13 mmhg, repeatability close to 96% and input range from 0 to 95.32 mmhg.