Hello everyone. complete newbie to electronics here. so I have been trying to make a breath controller with my arduino uno and the [MPS20N0040D] pressure sensor. the manufacturer suggests a differential amplifier setup with 4 100k ohm resistors which I have set up (and I will try to upload the relevant pictures in this post and I have labeled the wires hope it's not too difficult to read). I am also using a LM356 op-amp. I will also attach a picture of my testing code for the sensor and the serial monitor output. It is also important to mention at one point I had accidentally switched up my 5v and ground and had it the other way around. please share your informed opinion and please excuse the terrible soldering.
ps: although in the pictures it might look like some of the sensor pins are shorted I can assure you seeing it in person there is a lot of space between them and none of them are shorted.
Welcome to the forum.
Although you have posted some images of your project, there are still parts missing so that we can understand it better and help you.
How is the LM356 connected to your sensor?
The ideal would be to post a schematic of your project (as built).
From what I could understand from the datasheet of this sensor, it is purely resistive, so I "believe" that a polarity inversion would not damage it.
But the LM356 could have been damaged by the polarity inversion.
PS: I couldn't identify where pin 1 of the sensor is in the your image.
Have you checked if it is connected correctly?
This op amp., (LM356), needs +v and -V.
Did you connect both voltages?
Ref: https://www.ti.com/lit/ds/symlink/lf356-mil.pdf
Sensor:
Your project is mounted like this:
I don't see that happening with that sensor and your setup.
A 40Kpa sensor is more suited for blood pressure than for breath pressure differences.
A HX710, with a gain of 128, is commonly used with this sensor. See this page.
Your LM358 circuit has a gain of one, so even if you can get the opamp/Uno to output 2.5volt, you likely won't see a change with breath pressure.
Back to your circuit. It will work on a single supply, because the sensor always outputs a positive voltage. You should measure 2.5volt on pin 2 and 5 of the sensor, before connecting the LM358. After connecting the LM358, it should output 2.5volt as well.
Leo..
If the OP was using an LM358, he could actually use only one power supply, but since he is using an LM356, he will need 2 reverse polarity power supplies.
Hi, @yasinss
To make the sensor behave like a true balanced bridge, pins 1 and 6 of the sensor should be connected together.
Currently you are only using one half of the bridge, possibly not the half that has the pressure sensor active element.
Tom.. 
Thank you everyone for replying. my circuit currently looks like the picture bellow which is different from the schematic that the user @ruilviana provided main differences being that my sensor - Output is connected to - input of the op-amp and the + Output to the + input. Is my setup wrong and it should be like the schematic provided by @ruilviana ?
I have also checked the model number of my op-amp and it is indeed a LM358
so I apologize for mistakenly saying it was LM356. I have also provided both the operational amplifier and the sensor with 5V.
and as for the sensor itself being a bit inappropriate for the use case I mentioned I understand that it is indeed the case but there are certain issues with trying to get electronics like this in my part of the world and the closest thing I could find that I thought might work. my reasoning being I will probably get a smaller response than I would with the proper sensors and I will try to compensate for that by defining a smaller range in my arduino code. and also the hx710/711 op amps that are usually used with my sensor are not available in my country.
I have also connected the pins 1 and 6 as the user @TomGeorge suggested.
Thank you everyone for your guidance
there are no resistors between pin 5 and ground. that is mistake in the picture
In this case, it is completely pointless for the amplifier to have a gain of 1.0. You might as well just measure the voltage difference between two arms of the bridge.
Differential amplifiers with gain are discussed in many tutorials on the web. Here is one, randomly chosen: Fundamentals of Differential Amplifier using Op-amp