the project this summer is for us to design an oxygen calibration device. this project was initiated by the engineering freshman from rice and two prototypes were built. however this device though functional does not meet most of the design criteria. with their ideas and our ideas this summer we hope to complete and improve on the design or possibly come up with a different design all together.
lest see how this device works.the device is built to compare oxygen from the concentrator to the ambient oxygen which is at most 21%. zinc batteries used in hearing aid gadgets has been used to sense the amount of oxygen. the concentrated oxygen is compared to the reference ambient oxygen and the difference is amplified by a differential amplifier. the output from this is the voltage measured on the analogue meter. this relationship between concentration to the voltage is mapped on the oxygen concentration on the meter.by turning on the device an LED lights up and the concentration registered on the meter is 0 which is at 21% ambient oxygen level. blowing oxygen from the concentrator raises the the voltage of the battery being brown and the difference amplified shows the oxygen concentration and the doctor is able to tell the amount of oxygen being delivered to the patient.
technically the previous prototype left by the previous team worked but analytically it does not work this is because it never met the design criteria. the explicit goals that our project was to meet were portability, time to measure,durability, accuracy and cost and size. the previous team did a great job by coming up with a printed circuit board that oxycal revolution 2 takes over from to improve the design.
oxycal rev 2 has been seriously working on this board. we built all the components on the board and tested each individually component. the board could not work and an assumption was made that the soldering process was not well done. we then suggested to build a new board. the second board did not work either hence a lot of troubleshooting took place to establish the first cause. i must admit here that our team made a mistake in the first place. instead of the team to test the board before soldering any components on it, the team was just so happy and excitted to work on the project and we started soldering.
a number of things were identified and we have been working towards rectifying the problems. the most dominant cause for our board not working was the arrangement of the batteries on the printed circuit board. the batteries were arranged just opposite to each other which caused a lot of shorting on the circuit. another problem is airflow. the other problem is on the type of sensors used. the initial starting voltages of the zinc aid batteries are not the same which is a big problem with the analogue circuit.
oxycal came up with different ideas on how to address the problems and next time i am going to share some of the designs and changes that we have made to the board and the device.