Great research!! And It´s just a straw. I´m from Argentina, and what you say about the metal straw for mate Is true. But there Is more.... We even share the same straw with other people and hundreds of times!!! Isn´t that ecological? At first It´s kind of shocking but then you get used to it...

I liked the idea... It´s simple. Maybe car air fresheners could work as well.

Hi Kate... Well I went to a senior citizens club. I had the luck that they were In some kind of meeting (near 20 people). So I had a chance to ask them for some feedback... In resume I had two answers. The first, that matches both Tianqi's research and Andrea's Is that a woman wouldn´t wear them. Only If she has a serious problem with walking. Although I explained them that It was research model, and that at the end it would look prettier. They didn´t seem very convinced on trying them on. On the other hand. The men found it interesting, they would not only give it a try (they didn´t at that moment because they were In this meeting) but even one of them wanted to present It to a region seniors convention with over 200 people invited. I thank them for the invitation, but I prefered to have It a bit more elaborated.
They were concerned on the weight issue, but they felt It was ok
The other thing Is that most of them agreed that most of their falls was becuase of triping more than by sliping. That perhaps It would be better to work on that issue.
So... I can´t answer your questions yet. But I think I will be able to answer you back quite soon.