Several things to try.
First seek someplace that has both the tasks you currently are qualified to do and the new area you want to go to. Basically look for someplace where you have 60-70% of what the whole job is. Then show them how well you learn and that you are famliar with the new part of the job from your personal porjects.
The alternative is to apply for jobs in the new field and make your case for how what you know from the old field can benefit them. Also show them that you do have those skills from personal projects if you can. Be aware that if you go this route, you may have to explicitly tell them you are willing to take less money becasue then you are no longer a senior dev but a junior one. I have taken a pay cut to move into the field I wanted to move into and my pay has gone up a good bit since then becasue my new field high salary was higher than the high salary in my old field. It can be worth it financially in the long run to take a pay cut to get much more valuable experience.