Digital advertising is a useful tool for gauging interest in your problem and proposed solution. Not only does it connect your team with potential new users and research subjects but it also provides valuable quantitative data as you begin to investigate interest in your proposed solution. Of course, your ad will need to lead users somewhere so you'll have to have a landing page set up to collect data and tell users a bit more about your proposed solution.
In order to get the most out of your ad you need to pursue a specific goal and identify the metrics by which you'll measure success. For example, if you're looking to recruit users for product testing then obviously one metric will be the number of sign ups but you can also measure the number of click-throughs to understand how successful your ad was at commanding attention. Once you have your goals and metrics in mind, choose the networks that your users are most likely to frequent. Most networks have ad creation and targeting tools to help you direct your message to specific users and communities. Google AdWords is particularly useful and has a massive reach as do Facebook, LinkedIn, Pinterest and Instagram.