With the IPC and CPC classes you can find technology grouped by in fields! This can be powerful to find special Patents! But be careful, sometimes patents are not in the classes you expect them to be! Still you should include them in your searches!
You can filter by IPC classes or CPC classes. The CPC system is basically a more advanced system to group technology established by big patent offices!

I recommend you to search for the technology in the CPC classes!
Find them here:
https://worldwide.espacenet.com/patent/cpc-browser
