Fetal pulse oximeter for in situ monitoring during labour and birth

Abstract

The oxygen saturation of arterial blood which is normally measured by pulse oximeters is highly important. This paper introduces a miniaturization development of a non-invasive, reflective pulse oximeter. The aim of the project is to dramatically reduce the dimensions of a current device developed earlier already on the market whose size is 41x23x12 mm (LxWxH). A further purpose is to invent a pulse oximeter which can be used to constantly monitor the oxygen saturation of a fetus during its birth and the labour period. Although similar devices can be found on the market, our oximeter is smaller in size and there is no connection cable which can cause discomfort to the mother. This objective has been achieved by changing the main components of the prototype. Also, the Bluetooth module has been changed to an energy saving RF communication device. The main controller is also improved by adding a nanoWatt series QFN packaged PIC microcontroller to reduce power consumption. All of the analog electronic parts have been integrated into an ASIC (Applications Specific Integrated Circuit) chip. In addition to improvements in the hardware, new control software has been written. This reshuffling means that a new evaluation board has been made for testing and controlling the newly designed oximeter. It is also easy to use. In addition, a conventional PC can be used for data display and processing which highly reduces the cost.