Loo design has barely changed in 150 years – until now. Will people trade their privacy for the chance to find out exactly what is in their waste?For the past 10 years, Sonia Grego has been thinking about toilets – and more specifically what we deposit into them. “We are laser-focused on the analysis of stool,” says the Duke University research professor, with all the unselfconsciousness of someone used to talking about bodily functions