The First Fitbit: How the Health Tracker Was Engineered

It was December 2006. Twenty-nine-year-old entrepreneur James Park had simply bought a Wii recreation system. It included the Wii Nunchuk, a US $29 handheld controller with movement sensors that allow recreation gamers work together by transferring their our bodies—swinging at a baseball, say, or boxing with a digital accomplice.

Park turned obsessed along with his Wii.

“I used to be a tech-gadget geek,” he says. “Anybody holding that nunchuk was fascinated by the way it labored. It was the primary time that I had seen a compelling shopper use for accelerometers.”

After some time, although, Park noticed a flaw within the Wii: It bought you transferring, positive, but it surely trapped you in your lounge. What if, he thought, you may take what was cool in regards to the Wii and use it in a gadget that bought you out of the home?

The primary technology of Fitbit trackers shipped on this package deal in 2009. NewDealDesign

“That,” says Park, “was the aha second.” His thought turned Fitbit, an exercise tracker that has racked up gross sales of greater than 136 million items since its first iteration hit the market in late 2009.

However again to that “aha second.” Park shortly referred to as his buddy and colleague Eric Friedman. In 2002, the 2, each laptop scientists by coaching, had began a photo-sharing firm referred to as HeyPix, which they offered to CNET in 2005. They have been nonetheless working for CNET in 2006, but it surely wasn’t a foul time to consider doing one thing totally different.

Friedman cherished Park’s thought.

“My mom was an lively walker,” Friedman says. “She had a strolling group and at all times had a pedometer along with her. And my father labored with augmentative engineering [assistive technology] for the aged and handicapped. We’d performed with accelerometer tech earlier than. So it instantly made sense. We simply needed to refine it.”

The 2 left CNET, and in April 2007 they included the startup with Park as CEO and Friedman as chief expertise officer. Park and Friedman weren’t attempting to construct step one counter—mechanical pedometers date again to the Nineteen Sixties. They weren’t inventing the primary good exercise tracker—
BodyMedia, a medical gadget producer, had in 1999 included accelerometers with different sensors in an armband designed to measure energy burned. And Park and Friedman didn’t get a sensible shopper tracker to market first. In 2006, Nike had labored with Apple to launch the Nike+ for runners, a motion-tracking system that required a particular shoe and a receiver that plugged into an iPod

Fitbit’s founders James Park [left] and Eric Friedman launched their first product in 2009, when this photograph was taken. Peter DaSilva/The New York Occasions/Redux

Park wasn’t conscious of any of this when he thought of getting health out of the lounge, however the two shortly did their analysis and found out what they did and didn’t wish to do.

“We didn’t wish to create one thing costly, focused at athletes,” he says. “Or one thing that was dumb and never related to software program. And we wished one thing that would present social connection, like photograph sharing did.”

That one thing needed to be comfy to put on all day, be straightforward to make use of, add its knowledge seamlessly so the info may very well be tracked and shared with buddies, and barely want charging. Not a straightforward mixture of necessities.

“It’s a kind of issues the place the easier you get, the tougher it turns into to design one thing properly,” Park says.

The primary Fitbit was designed for ladies

The primary design choice was the largest one. The place on the physique did they anticipate folks to place this wearable? They weren’t going to ask folks to purchase particular footwear, just like the Nike+, or put on a thick band on their higher arms, like BodyMedia’s tracker.

They employed
NewDealDesign to determine a few of these particulars.

“In our first two weeks, after a number of discussions with Eric and James, we determined that the undertaking was going to be geared to ladies,” says Gadi Amit, president and principal designer of NewDealDesign. “That call was the motive force of the shape issue.”

“We wished to start out with one thing acquainted to folks,” Park says, “and other people tended to clip pedometers to their belts.” So a clip-on gadget made sense. However ladies usually don’t put on belts.

To do what it wanted to do, the clip-on gadget must comprise a roughly 2.5-by-2.5-centimeter (1-by-1-inch) printed circuit board, Amit remembers. The large breakthrough got here when the crew determined to separate the electronics and the battery, which in most units are stacked. “By doing that, and elongating it a bit, we discovered that girls may put it anyplace,” Amit says. “Many would put it of their bras, so we focused the design to suit a bra within the middle entrance, buying dozens of bras for testing.”

The choice to design for ladies additionally drove the general look, to “subdue the person interface,” as Amit places it. They hid a low-resolution monochrome OLED show behind a steady plastic cowl, with the show lighting up solely once you requested it to. This selection helped give the gadget a formidable battery life.

The earliest Fitbit units used an animated flower as a progress indicator. NewDealDesign

Additionally they got here up with the concept of a flower as a progress indicator—impressed, Park says, by the
Tamagotchi, one of many greatest toy fads of the late Nineteen Nineties. “So we had a bit of animated flower that might shrink or develop primarily based on how lively you have been,” Park explains.

And after a lot dialogue over controls, the group gave the unique Fitbit only one button.

Hiring an EE—from Dad—to design Fitbit’s circuitry

Park and Friedman knew sufficient about electronics to construct a crude prototype, “stuffing electronics right into a field product of cut-up balsam wooden,” Park says. However in addition they knew that they wanted to herald an actual electrical engineer to develop the {hardware}.

Fortuitously, they knew simply whom to name. Friedman’s father, Mark, had for years been working to develop a tool to be used in nursing properties, to remotely monitor the place of bed-bound sufferers. Mark’s accomplice on this effort was Randy Casciola, an electronics engineer and at the moment president of Morewood Design Labs.

Eric referred to as his dad, instructed him in regards to the gadget he and Park envisioned, and requested if he and Casciola may construct a prototype.

“Mark and I believed we’d construct a quick-and-dirty prototype, one thing they may get sensor knowledge from and use for creating software program. After which they’d go off to Asia and get it miniaturized there,” Casciola remembers. “However one revision led to a different.” Casciola ended up engaged on circuit designs for Fitbits just about full time till the sale of the corporate to Google, introduced in 2019 and accomplished in early 2021.

“We noticed some fairly scary producers. Soiled amenities, flash marks on their injection-molded plastics, very low precision.”
—James Park

“We have been simply two little guys in a bit of workplace in Pittsburgh,” Casciola says. “Earlier than Fitbit got here alongside, we had realized that our nursing-home factor wasn’t more likely to ever be a product and had began taking over some consulting work. I had no thought Fitbit would turn into a family identify. I similar to engaged on something, whether or not I feel it’s a good suggestion or not, and even whether or not somebody is paying me or not.”

The earliest prototypes have been fairly giant, about 10 by 15 cm, Casciola says. They have been large enough to simply hook as much as take a look at tools, but sufficiently small to strap on to a keen take a look at topic.

After that, Park and Eric Friedman—together with Casciola, two contracted software program engineers, and a mechanical design agency—struggled with turning the cumbersome prototype right into a small and modern gadget that counted steps, saved knowledge till it may very well be uploaded after which transmitted it seamlessly, had a easy person interface, and didn’t want every day charging.

“Determining the precise stability of battery life, dimension, and functionality saved us occupied for a couple of yr,” Park says.

The Fitbit prototype, sitting on its charger, booted up for the primary time in December 2008. James Park

After deciding to incorporate a radio transmitter, they made an enormous transfer: They turned away from the Bluetooth commonplace for wi-fi communications in favor of
the ANT protocol, a expertise developed by Garmin that used far much less energy. That meant the Fitbit wouldn’t be capable of add to computer systems instantly. As a substitute, the crew designed their very own base station, which may very well be left plugged into a pc and would seize knowledge anytime the Fitbit wearer handed inside vary.

Casciola didn’t have experience in radio-frequency engineering, so he relied on the provider of the ANT radio chips:
Nordic Semiconductor, in Trondheim, Norway.

“They’d do a design evaluate of the circuit board format,” he explains. “Then we’d ship our {hardware} to Norway. They’d do RF measurements on it and inform me find out how to tweak the values of the capacitors and conductors within the RF chain, and I might replace the schematic. It’s half engineering and half black magic to get this RF stuff working.”

One other commonplace they didn’t use was the ever-present USB charging connection.

“We couldn’t use USB,” Park says. “It simply took up an excessive amount of quantity. Anyone truly stated to us, ‘No matter you do, don’t design a customized charging system as a result of it’ll be a ache, it’ll be tremendous costly.’ However we went forward and constructed one. And it was a ache and tremendous costly, however I feel it added a degree of magic. You simply plopped your gadget on [the charger]. It seemed lovely, and it labored constantly.”

A lot of the electronics they used have been off the shelf, together with a 16-bit Texas Devices MSP430 microprocessor, and 92 kilobytes of flash reminiscence and 4 kb of RAM to carry the working system, the remainder of the code, all of the graphics, and a minimum of seven days’ value of collected knowledge.

The Fitbit was designed to withstand sweat, they usually usually survived showers and fast dips, says Friedman. “However sizzling tubs have been the bane of our existence. Individuals clipped it to their swimsuits and forgot that they had it on after they jumped into the new tub.”

Fitbit’s demo or die second

Up thus far, the corporate was surviving on $400,000 invested by Park, Friedman, and some individuals who had backed their earlier firm. However extra money can be wanted to ramp up manufacturing. And so a important subsequent step can be a reside public demo, which they scheduled for the TechCrunch convention in San Francisco in September 2008.

Dwell demonstrations of recent applied sciences are at all times dangerous, and this one walked proper as much as the sting of catastrophe. The plan was to ask an viewers member to name out a quantity, after which Park, carrying the prototype in its balsa-wood field, would stroll that variety of steps. The rely would sync wirelessly to a laptop computer projecting to a display on stage. When Friedman hit refresh on the browser, the step rely would seem on the display. What may go flawed?

So much. Friedman explains: “You assume counting steps is straightforward, however let’s say you do three steps. One, two, three. If you carry your toes collectively, is {that a} step or is that the top? It’s a lot simpler to rely 1,000 steps than it’s to do 10 steps. If I stroll 10 steps and am off by one, that’s a obtrusive error. With 1,000, that variance turns into noise.”

The primary semi-assembled Fitbit information its inaugural step rely. James Park

After numerous observe, the 2 thought they may pull it off. Then got here the demo. “Whereas I used to be strolling, the laptop computer crashed,” Park says. “I wasn’t conscious of that. I used to be simply strolling fortunately. Eric needed to reboot all the pieces whereas I used to be nonetheless strolling. However the numbers confirmed up; I don’t assume anybody besides Eric realized what had occurred.”

That day, some 2,000 preorders poured in. And Fitbit closed a $2 million spherical of enterprise funding the following month.

Although Park and Friedman had hoped to get Fitbits into customers’ fingers—or clipped onto their bras—by Christmas of 2008, they missed that deadline by a yr.

The algorithms that decide Fitbit’s rely

A part of Fitbit’s problem of getting from prototype to shippable product was software program growth. They couldn’t anticipate customers to stroll as exactly as Park did for the demo. As a substitute, the gadget’s algorithms wanted to find out what a step was and what was a distinct sort of movement—say, somebody scratching their nostril.

“Information assortment was tough,” Park says. “Initially, it was numerous us carrying prototype units doing quite a lot of totally different actions. Our head of analysis, Shelten Yuen, would observe, videotaping so we may return and rely the precise variety of steps taken. We might put on a number of units concurrently, to check the info collects in opposition to one another.”

Friedman remembers one such outing. “James was tethered to the pc, and he was pretending to stroll his canine across the Haight [in San Francisco], narrating this little play that he’s placing on: ‘OK, I’m going to cease. The canine goes to pee on this tree. And now he’s going over there.’ The wonderful thing about San Francisco is that no one appears surprisingly at two guys tethered collectively strolling round speaking to themselves.”

“Older folks are likely to have an irregular cadence—to the gadget, older folks look so much like buses going over potholes.”–James Park

“Pushing child strollers was a difficulty,” as a result of the wearer’s arms aren’t swinging, Park says. “So one in all our guys put an ET doll in a child stroller and walked everywhere in the metropolis with it.”

Street noise was one other huge situation. “Yuen, who was engaged on the algorithms, was primarily based in Cambridge, Mass.,” Park says. “They’ve extra potholes than we do. When he took the bus, the bus would hit the potholes and [the device would] be bouncing alongside, registering steps.” They couldn’t simply repair the difficulty by searching for a daily cadence to rely steps, he provides, as a result of not everybody has a daily cadence. “Older folks are likely to have an irregular cadence—to the gadget, older folks look so much like buses going over potholes.”

Fitbit’s founders enter the world of producing

A shopper gadget means mass manufacturing, probably in big portions. They talked to numerous contract-manufacturing corporations, Park remembers. They realized that as a startup with an unclear future market, they wouldn’t be of curiosity to the highest tier of producers. However they couldn’t go together with the lowest-budget operations, as a result of they wanted an affordable degree of high quality.

“We noticed some fairly scary producers,” Park stated. “Soiled amenities, flash marks on their injection-molded plastics [a sign of a bad seal or other errors], very low precision.” They ultimately discovered a small producer that was “fairly good however nonetheless hungry for enterprise.” The producer was headquartered in Singapore, whereas their surface-mount provider, which put parts instantly onto printed circuit boards, was in Batam, Indonesia.

Staff assemble Fitbits by hand in October of 2008. James Park

Working with that producer, Park and Friedman made some tweaks within the design of the circuitry and the form of the case. They struggled over find out how to preserve water—and sweat—out of the gadget, deciding on ultrasonic welding for the case and including a spray-on coating for the circuitry after some units have been returned with corrosion on the electronics. That required tweaking the format to verify the coating would get between the chips. The coating on every circuit board needed to be checked and touched up by hand. After they realized that the coating elevated the peak of the chips, they needed to tweak the format some extra.

In December 2009, only a week earlier than the ship date, Fitbits started rolling off the manufacturing line.

“I used to be in a resort room in Singapore testing one of many first totally built-in units,” Park says. “And it wasn’t syncing to my laptop. Then I put the gadget proper subsequent to the bottom station, and it began to sync. Okay, that’s good, however what was the utmost distance it may sync? And that turned out to be actually only a few inches. In each different take a look at we had completed, it was advantageous. It may sync from 15 or 20 toes [5 or 6 meters] away.”

The issue, Park ultimately found out, occurred when the 2 halves of the Fitbit case have been ultrasonically welded collectively. In earlier syncing exams, the instances had been left unsealed. The sealing course of pushed the halves nearer collectively, in order that the cable for the show touched or almost touched the antenna printed on the circuit board, which affected the radio sign. Park tried squeezing the halves collectively on an unsealed unit and reproduced the issue.

Getting the primary technology of Fitbits into mass manufacturing required some last-minute troubleshooting. Fitbit cofounder James Park [top, standing in center] helps debug a tool on the producer shortly earlier than the product’s 2009 launch. Early items from the manufacturing line are proven partially assembled [bottom]. James Park

“I believed, if we may simply push that cable away from the antenna, we’d be okay,” Park stated. “The one factor I may discover in my resort room to do this was bathroom paper. So I rolled up some bathroom paper actually tight and shoved it in between the cable and the antenna. That appeared to work, although I wasn’t actually assured.”

Park went to the manufacturing facility the following day to debate the issue—and his resolution—with the manufacturing crew. They refined his repair—changing the bathroom paper with a tiny slice of froth—and that’s how the primary technology of Fitbits shipped.

Fitbit’s quick evolution

The corporate offered about 5,000 of these $99 first-generation items in 2009, and greater than 10 occasions that quantity in 2010. The rollout wasn’t solely easy. Casciola remembers that Fitbit’s logistics middle was sending him a stunning variety of corroded units that had been returned by clients. Casciola’s process was to tear them down and diagnose the issue.

“One of many contacts on the gadget, over time, was rising a inexperienced corrosion,” Casciola says. “However the different two contacts weren’t.” It turned out the issue got here from Casciola’s design of the system-reset set off, which allowed customers to reset the gadget and not using a reset button or a detachable battery. “Inevitably,” Casciola says, “firmware goes to crash. When you possibly can’t take the battery out, you need to have one other method of forcing a reset; you don’t wish to have somebody ready six days for the battery to expire earlier than restarting.”

The reset that Casciola designed was “a button on the charging station that you may poke with a paper clip. If you happen to did this with the tracker sitting on the charger, it will reset. After all, we needed to have a method for the tracker to see that sign. Once I designed the circuit to permit for that, I ended up with a nominal voltage on one pin.” This low voltage was inflicting the corrosion.

“If you happen to clipped the tracker onto sweaty clothes—keep in mind, sweat has a excessive salt content material—a really tiny present would stream,” says Casciola. “It was simply fractions of a microamp, not sufficient to trigger a reset, however sufficient, over time, to trigger greenish corrosion.”

Cofounders Eric Friedman [left] and James Park go to Fitbit’s producer in December of 2008. James Park

On the 2012 technology of the Fitbit, referred to as the Fitbit One, Casciola added a brand new kind of chip, one which hadn’t been out there when he was engaged on the unique design. It allowed the one button to set off a reset when it was held down for some seconds whereas the gadget was sitting on the charger. That eradicated the necessity for the lively pin.

The charging interface was the supply of one other early drawback. Within the preliminary design, the trim of the Fitbit’s plastic casing was painted with chrome. “We initially wished an precise metallic trim,” Friedman says, “however that interfered with the radio sign.”

Chrome wasn’t an amazing selection both. “It prompted issues with the charger interface,” Park provides. “We needed to do numerous work to forestall shorting there.”

They dropped the chrome after some tens of hundreds of items have been shipped—after which bought compliments from purchasers in regards to the new, chrome-less look.

Evolution occurred shortly, notably in the best way the gadget transmitted knowledge. In 2012, when Bluetooth LE turned broadly out there as a brand new low-power communications commonplace, the bottom station was changed by a small Bluetooth communications dongle. And ultimately the dongles disappeared altogether.

“We had an enormous debate about whether or not or to not preserve transport that dongle,” Park says. “Its value was vital, and for those who had a latest iPhone, you didn’t want it. However we didn’t need somebody shopping for the gadget after which returning it as a result of their cellphone couldn’t join.” The crew carefully tracked the penetration price of Bluetooth LE in cellphones; after they felt that quantity was excessive sufficient, they killed off the dongle.

Fitbit’s wrist-ward migration

After a number of iterations of the unique Fitbit design, typically referred to as the “clip” for its form, the health tracker moved to the wrist. This wasn’t a matter of merely redesigning the best way the gadget hooked up to the physique however a rethinking of algorithms.

The impetus got here from some customers’ want to higher monitor their sleep. The Fitbit’s algorithms allowed it to establish sleep patterns, a design selection that, Park says, “was pivotal, as a result of it modified the gadget from being simply an exercise tracker to an all-day wellness tracker.” However nightclothes didn’t provide apparent spots for attachment. So the Fitbit shipped with a skinny cloth wristband meant to be used simply at night time. Customers started asking buyer assist if they may preserve the wristband on across the clock. The reply was no; Fitbit’s step-counting algorithms on the time didn’t assist that.

“My father, who turned 80 on July 5, is fixated on his step rely. From 11 at night time till midnight, he’s within the parking storage, going up flights of stairs. And he’s in higher form than I ever keep in mind him.” —Eric Friedman

In the meantime, a cultural phenomenon was underway. Within the mid-2000s, yellow
Livestrong bracelets, made out of silicone and offered to assist most cancers analysis, have been all of a sudden in all places. Different causes and actions jumped on the development with their very own brightly coloured wristbands. By early 2013, Fitbit, together with opponents Nike and Jawbone, had launched the Flex, a wrist-worn health tracker in roughly the identical type as these fashionable bracelets, as soon as once more designed by NewDealDesign.

A no-button person interface for the Fitbit Flex

The Flex’s interface was even easier than the unique Fitbit’s one button and OLED display: It had no buttons and no display, simply 5 LEDs organized in a row and a vibrating motor. To vary modes, you tapped on the floor.

“We didn’t wish to substitute folks’s watches,” Park says. The expertise wasn’t but able to “construct a compelling gadget—one which had an enormous display and the compute energy to drive actually superb interactions on the wrist that might be worthy of that display. The expertise developments didn’t converge to make that potential till 2014 or 2015.”

The Fitbit Flex [right], the primary Fitbit designed to be worn on the wrist, was launched in 2013. It had no buttons and no display. Customers managed it by tapping; 5 LEDs indicated progress towards a step rely chosen through an app [left]. iStock

“The quantity of stuff the crew was in a position to convey with simply the LEDs was superb,” Friedman remembers. “The standing of the place you’re in the direction of reaching your [step] aim, that’s apparent. However [also] the lights biking to point out that it’s looking for one thing, the vibrating once you hit your step aim, issues like that.”

The faucet a part of the interface, although, was “probably one thing we didn’t get solely proper,” Park concedes. It took a lot fine-tuning of algorithms after the launch to higher kind out what was
not tapping—like applauding. Much more necessary, some customers couldn’t fairly intuit the precise option to faucet.

“If it really works for 98 % of your customers, however you’re rising to thousands and thousands of customers, 2 % actually begins including up,” Park says. They introduced the button again for the following technology of Fitbit units.

And the remaining is historical past

In 2010, its first full yr available on the market, the Fitbit offered some 50,000 items. Fitbit gross sales peaked in 2015, with nearly 23 million units offered that yr, in line with
Statista. Since then, there’s been a little bit of a drop-off, as multifunctional good watches have come down in worth and grown in recognition and Fitbit knockoffs entered the market. In 2021, Fitbit nonetheless boasted greater than 31 million lively customers, in line with Market.us.Media. And Fitbit might now be using the development again to simplicity, as folks discover themselves eager to do away with distractions and transfer again to easier units. I see this taking place in my circle of relatives: My smartwatch-wearing daughter traded in that wearable for a Fitbit Cost 6 earlier this yr.

Fitbit went public in 2015 at a valuation of $4.1 billion. In 2021 Google accomplished its $2.1 billion buy of the corporate and absorbed it into its {hardware} division. In April of this yr, Park and Friedman left Google. Early retirement? Hardly. The 2, now age 47, have began a brand new firm that’s at the moment in stealth mode.

The concept of encouraging folks to be lively by electronically monitoring steps has had endurance.

“My father, who turned 80 on July 5, is fixated on his step rely,” Friedman says. “From 11 at night time till midnight, he’s within the parking storage, going up flights of stairs. And he’s in higher form than I ever keep in mind him.”

What may very well be a greater reward than that?