Supersonic planes, food harvesting robots and instant HIV diagnosis were some of the ideas that wowed us on Demo Day 2 for Y Combinator’s Winter 2016 batch. We queried investors and TechCrunch’s writers to come up with our top 8 picks from all 59 startups that presented. Check out our coverage of the 60 YC startups from Tuesday, plus our 7 favorites. Additional reporting by Megan Rose Dickey and Sarah Buhr.