I am sure that you’ve heard of the MacArthur Fellowships.   You know, the ones that are also called the “Genius Grants”.    They are awarded annually to 20 to 30 folks, all of whom are considered to be extremely creative.  The prize is for some $ 625K awarded over the course of 5 years.

Oh, and don’t think about applying for these grants.  You can’t.  They find you- and award them to scientists, artists, and the like.

Well, today we’ll talk about two folks who were so named.  Daniela Rus, an MIT professor who was awarded the Fellowship in 2002 and L. Mahadevan, a Harvard prof who was so named in 2009.

So, Mahadevan was “fired” as a hair comber by his 5 year old daughter.  His technique involved more pain than providing “ruliness” to her tangled hair.  But, that was 20 years ago.

But, recently (as in 3 years ago), the problem resurfaced in his mind and he assembled a team to study the problem.  And, while hair brushing is not a new art (it dates back to the first humans) and involves some hundreds of millions of dollars a year (the hairbrush market is huge), Mahadevan’s team has made some progress.

The problem came down to describing a tangle.  Not just a hair tangle, but tangles like those that are associated with Alzheimer’s disease, bird’s nests, DNA helices, etc.  Actually, the problem came down to how one “detangles” something.

And, as is true for most problem solutions, the trick was to reduce the issue to its basics.  In this case- two strands of wavy hair that were entwined as if they were a DNA helix.   Running a comb tine through the strands demonstrated that moving the comb down stressed the scalp and intensified the tangle.  Which meant a new property needed to be defined- the “link density”.  Higher link densities were associated with worse tangles- and that meant combing the hair hurt more.

Of course, it also meant that a complex mathematical formula would be developed, crossing the boundaries of topology, geometry, and mechanics- and a theorem called the Calugareanu-Fuller-White theorem.  But, of course, it also led to a publication.   Dr. L. Madevan along with his two PhD candidates,  T. Plumb-Reyes, N. Charles, published their study results in the journal  “Soft Science”, in an article entitled:  Combing a double helix.

The trick?  One I learned brushing my kids’ hair some three and four decades ago is to use a short stroke, starting at the BOTTOM of the hair.  When that’s detangled, you work your way up with longer and longer strokes.  (Mahadevan et. al. demonstrated that this technique is the “optimum” solution.)

Well, if a Harvard prof is getting into the act, you know that an MIT scholar can’t be far behind.  And, Dr. Daniela Rus, a 2002 McArthur Fellow, joined in the act.  But, her efforts were more along the lines of using technology to get the job done, not a theoretical pursuit.

Her improvement to the problem involved a robotic arm with a brush that with the aid of sensors (that detect tension- which in a real life person would be pain, but the hair being tested is actually on mannequins that can’t register an iota of pain) and cameras to see how curly the hair is, detangles a slew of straight and curly wigs on the mannequins.   All based on Mahadevan’s double helix solution.

Daniela Rus and her postdoc, Dr. Josie Hughes, along with Mahadevan and his two PhD candidates presented the results from the robotic development at the IEEE Conference on Soft Robotics (RoboSoft) in Edinburgh earlier this month (April 2022).

Rus hopes to have her robotic brush system available for seniors and those with disabilities- to ensure they are among the best groomed- and least pained- folks around.  And, to free up the staff in nursing and extended care facilities from some of the personal care time grooming hair.

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