Boba Blocker Straw Concept
With a love of milk tea w/ boba and a desire to have the best of both worlds, I set out to design a straw that would allow you to choose when you wanted to include the pearls in your sips
After iterating through several designs of straw caps (right), I had to put the project on pause to work on other things, but am eager to get back to it when I have the chance!
I love boba, it’s a weekly Saturday ritual for me and nothing gives me quite the same rush as black tea and sugar. One such weekend, my wife and I were enjoying some milk tea at a nearby fried chicken sandwich spot, taking bites of crunchy chicken followed by swigs of cold tea. The combination was divine as usual, the only issue was the during those swigs a flood of tapioca balls would float their way up the straw, causing a confusing mix of sweet-and-chewy pearls with savory-and-crunchy chicken. It’s not my favorite texture mix, and since we would likely be frequenting this restaurant as part of our weekly milk tea routine, I thought about how I could separate the liquid tea from the solid boba when I wanted a clean cooling liquid sip, then switch to letting the boba pearls in for that sweet chew. One might say, “just get it without boba”, or “just push the straw opening against the wall of the cup”, but the cup wall method does not work consistently, and requires a physical (albeit slight) effort, and I want the pearls as much as the tea, I just want to have more choice of when to bring them into the party bite-to-bite.
Dumb idea? Probably. But worth pursuing nonetheless. I imagined a valve mechanism, one that partially closes enough to block the balls but not the liquid, with a lever on the outside of the straw to control the position. I originally considered using a stainless steel straw with a rounded cavity towards one end, thinking I could squeeze a silicone valve into it. The steel straw would be too hard (and expensive) to manufacturer with the rounded cavity, and so I pivoted the design to instead be a cap that would slide onto the end of a typical boba straw, made of two silicone parts; an outer sleeve with the rounded valve cavity to grip the straw and house the valve, and the inner valve that would do the boba blocking. This reduced the problem of manufacturing because I would be able to silicone cast both parts in a relatively easy way, as well as made it more adaptable and portable.
I made a few prototypes, shown above and right, and was iterating through the design, and had a few optimizations to try, but came to the realization that even if I blocked the pearls from exiting the tube, they would still travel up it, causing a flow restriction as they pile into the straw and constrict the path for liquid to flow. To solve this, the cleanest way to separate the pearls would be at the bottom end of the straw, but since that was moving away from my architecture I put the project on hold. I would still like to try the straw cap idea, and pick it back up when I have the chance.
The original stainless steel CAD model (left), with a cross-section of the valve mechanism in it’s closed state. Because the valve lever rotates with the valve, it significantly reduces the allowable travel of the valve before there is a leak risk. This could be avoided if the lever is through the axis of rotation, and I will pursue that design change next.
One of the original designs was a valve that swapped between completely open cylinder to a boba blocking grate (left). However this geometry would also allow liquid to leak through the gap in the housing that the lever has to poke out of, so the updated design to improve this risk is shown (right), which just partially closes the valve to restrict the path size.
An early sketch of the concept, it was hard to visualize the valve geometry in 2D so I moved to mocking it up in CAD quicker than other projects