I love the question "what technologies/frameworks should I use to build my new product?" because it is one of the only questions for which there is almost always one correct answer for everyone. That answer is 'whichever lets you get a minimum viable product released the fastest.' To sorta-quote Eric Ries, most products do not survive their first encounter with the users. You should use whichever tech you are the most agile with and get a concept app out and into people's hands as fast as possible. After you pivot 15 times and actually know what your immediate and near-term requirements are...THEN you can start looking at going off into new territory if there's a better solution than PHP for your particular case. I'd be spending much more time trying to be sure that you are building something that people actually want and that you can create a business around rather than learning a new language. I'm happy to talk over strategy anytime :0)

In addition to the costs noted by Dr. Young for "investigator fees" you should also consider whether or not you have the proper operating framework in place across your organization to meet documentation and procedural requirements. Your entire SDLC needs to be validated before you can even begin to gather data about "efficacy" that you might want to use in a submission, marketing claim, or in support of a regulatory application in the future. Having released a mobile application in this space in addition to several web apps, I'm happy to discuss more details with you if you like :0)