Dear Vivek,

To measure fluid pressure a strain guage sensor is the best and economical bet.Then this should be interfaced with an instrumenatation amplifier and finally the output digitized for display.

In fact trying to develop a digital pressure guage is something like trying to develop a dry cell all by yourself. You can do it - but not worth it unless it is to learn the subject. Top class technology is available ready made at a much lower cost as compared to the time and effort cost of a prototype.

If you can give me the required working pressure and the display resolution that you need I can give you many solutions.

( And dont ever try to read pressure with a condensor microphone as someone suggested )

Raghu