Should I try to avoid being the single author of my patent/paper?
As the proud author of many papers with all sorts of numbers of authors, anywhere from just myself to dozens of co-authors, I see no reason to avoid being a single author.  

In evaluating a researcher, I would only have concern with their ability to collaborate if they show a preponderance of single-author papers.  If somebody has a mix of single-author and multi-author papers, then my reaction will instead be more positive, because it shows they are both capable of collaboration and also capable of initiating truly independent work.

So: go for it on your single authorship (and/or inventorship)!  Just make certain that your co-workers agree with you that they should not be authors/inventors, or else you may have an entirely different type of problem on your hands.