Read and register spectrophotometer measurements using Arduino

Hi everyone,

We have a simple UV spectrophotometer in our lab that we use to measure protein concentration in solutions (the system is described in the upper illustration in the attached figure). Basically, the solution is continuously sucked by a peristaltic pump, passes through a spectrophotometer that measure the light absorption as an increase in the resistance (I think), and then this resistance is read using a multimeter.

I want to use Arduino to collect these data as a function of time (see the lower illustration) and store it in a text file. I also would like to monitor these readings in real time in my computer and, if possible, to plot the graph in real time.

I am really new with Arduino, electronics and programming, so I would like to know if you have any ideas to help me to solve this problem.

My apologies if I am posting in the wrong area.

Thank you very much.

Best regards,


If you're new to Arduino, you shouldn't really start with a project like this.
Buy an Uno and/or a starter kit with some sensors, and work your way through that first.
There are examples in the Arduino IDE.
Within weeks you will see that it's not as hard as it seems.
Then you have a better understanding of what can be done for your project.

Thanks for your answer, Leo.

Actually, I am not totally ignorant about Arduino. I already have a starter kit that I acquired a few years ago and I followed some tutorials and learned a little bit at the time, but over time I stopped working with it. Now I have this issue and I would like to use Arduino to facilitate my life. Since currently it is not my priority to dedicate a large amount of time in this project (since it is not crucial), I am asking some tips from more experienced people to speed up the solution.

Thank you again,


So you have to use an external DMM to measure the output voltage of this machine.

What is the voltage range.

Does the machine have metal (ground) on the outside.

Can you measure any resistance between ONE output pin and ground when the machine is OFF.
It is important to know if the output is ground referred or not.

Or what is the output voltage on each output pin with the black pin held to a metal part of the machine.