Circuit design for cervical dilation monitoring with time varying inductor sensor

Abstract

A pregnant female has a 42 week long gestation period for child birth. This period is divided in three categories: preterm, term and post term. A preterm labour is a labour that happens before the 37th week but after the 20th week. A preterm labour does not always lead to a premature delivery but it is responsible for more than half of the premature births. Preterm delivery can be prevented if a preterm labour is detected after the 23rd week in gestation. Cervical dilation is a good indicator of the beginning of labor since it is an important precursor to delivery. An electronic circuit system is used to continuously monitor the dilation of the cervix of a pregnant female approaching labor and delivery. This circuit consist of a time varying inductor as a primary sensor. The output voltage obtained from this inductor is further rectified and filtered in order to get a smooth DC level and it can further be used as an indicator for dilation of cervix of a pregnant female approaching labor and delivery. In this report we have derived this electronic circuit and analysed the behaviour of time varying inductor mathematically such that output voltage remains linear in the entire working range.