Over the years MobiHealthNews has reported on a number of health and medical sensors that seemed incredible upon first read.

Back in 2009 we first wrote about an ingestible sensor from Redwood City, California-based Proteus Digital Health (then called Proteus Biomedical) that could wirelessly transmit a signal to a bodyworn patch when a person's stomach acid broke it down -- a bite-sized medication adherence tracker. From the start, Proteus dealt with "Big Brother" headlines and even some accusing them of creating the "Mark of the Beast" as described in The Book of Revelation, but MobiHealthNews readers never questioned the technology's plausibility. In the meantime, Proteus has gone on to secure regulatory clearance for its system in various markets, publish efficacy studies, and win customers. Political and religious concerns aside -- it never was vaporware.

Early in 2012 MobiHealthNews wrote about another seemingly too good to be true medical sensor. Stanford researchers said they had developed tiny medical sensors that could swim through the bloodstream to deliver drugs, remove plaque build-up, and more. In October 2012 The Qualcomm Foundation announced that it had awarded San Diego's Scripps Translational Science Institute (STSI) $3.75 million to fund various clinical trials, including one that leveraged this technology. Scripps' Dr. Eric Topol has said the institution is working on a project to put a nanosensor in the bloodstream that could pick up when the artery lining sheds cells, which is an early indication of an imminent heart attack. “And then you will get on your phone a special heart attack ringtone [that] will warn you within a week or two weeks that you are very liable to have a heart attack,” Topol told NBC News.

This week, however, Dr. Topol and many other MobiHealthNews readers called into question a new venture in the world of mobile-enabled medical sensors. A small Canadian startup founded by three recent graduates of Waterloo University announced this week that they had developed a wristworn device that can -- among other things -- passively track nutrition, including calories, carbs, protein, and fat. Airo, as the device will be named, uses an optical sensor to detect signatures of various metabolites to infer the wearer's nutrition habits, the startup's founder and CEO Abhilash Jayakumar told MobiHealthNews in an interview. On Twitter, Topol seemed puzzled by the announcement:

Can a wristband accurately track caloric intake? http://t.co/OImrZBxgX6 "wavelengths of light..blood..detect metabolites"? @MobiHealthNews

— Eric Topol (@EricTopol) October 29, 2013

One MobiHealthNews reader commented, "C'est des conneries!" (That's French for "B.S.") "This story is essentially the 'cold fusion' of wearable devices." Another wrote in: "I find it very difficult to believe this thing actually works. There are way too many variables... If they actually managed to get this to work it would be a revolutionary product that would sell for a lot more than $200."

Still another reader, who has been working on a similar problem to what Airo claims to have solved, told me that “if they can optically measure that through the skin they will win the Nobel Prize". He went on to explain that "reflective or transmissive light detection through the skin is a very difficult problem. Billions of dollars have been spent by more than 100 companies in the non-invasive glucose measurement market to measure analytes through the skin -- without success. Add the complexity of a [relatively] loosely fitting wristband -- it makes their story even more difficult to believe is theoretically possible, let alone credible."

Still, the startup has set expectations very high for a wristband device that no one has yet seen in action. Jayakumar said the team intends to begin testing soon, but so far the device has proven a hit among colleagues at his coworking space, he said. To make matters worse from an optics perspective, Airo is already taking pre-orders for its device, which it hopes to ship a year from now -- in the fall of 2014.

So, it might be a year until we figure out exactly what the Airo can do. Until then with "cold fusion" and "Nobel Prize" getting thrown around in response -- skepticism abounds. Here's one thing the three Airo founders can take solace in: At least no one's accusing them of creating the "Mark of the Beast".