Start-up accelerator TechStars held its annual Demo Day in New York on Thursday, with 13 young companies presenting their ideas to a room of potential investors.

Demo Day is a culmination of the work the start-ups have done over the last three months with menotors at TechStars, fine-tuning the ideas to become the next big thing. We were keeping an eye on some of the reactions to the start-ups' presentations.

Here are some of the interesting things we heard today.