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 permit recreation gamers work together by transferring their our bodies—swinging at a baseball, say, or boxing with a digital associate.

Park grew to become obsessed together 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 can take what was cool in regards to the Wii and use it in a gadget that bought you out of the home?

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

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

However again to that “aha second.” Park shortly known as his pal and colleague Eric Friedman. In 2002, the 2, each pc scientists by coaching, had began a photo-sharing firm known as HeyPix, which they bought 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 energetic walker,” Friedman says. “She had a strolling group and at all times had a pedometer together 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 know-how officer. Park and Friedman weren’t making an attempt to construct step one counter—mechanical pedometers date again to the 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 wise 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 Instances/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 needed one thing that would present social connection, like photograph sharing did.”

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

“It’s a type of issues the place the easier you get, the more durable it turns into to design one thing nicely,” Park says.

The primary Fitbit was designed for ladies

The primary design resolution was the largest one. The place on the physique did they count on individuals to place this wearable? They weren’t going to ask individuals 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 challenge 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 needed to start out with one thing acquainted to individuals,” Park says, “and folks tended to clip pedometers to their belts.” So a clip-on gadget made sense. However ladies typically don’t put on belts.

To do what it wanted to do, the clip-on gadget must include a roughly 2.5-by-2.5-centimeter (1-by-1-inch) printed circuit board, Amit recollects. 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 might put it wherever,” Amit says. “Many would put it of their bras, so we focused the design to suit a bra within the heart 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 if you requested it to. This alternative 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 thought of a flower as a progress indicator—impressed, Park says, by the
Tamagotchi, one of many largest toy fads of the late Nineties. “So we had just a little animated flower that may shrink or develop primarily based on how energetic 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 fabricated from cut-up balsam wooden,” Park says. However additionally they knew that they wanted to herald an actual electrical engineer to develop the {hardware}.

Happily, 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 associate on this effort was Randy Casciola, an electronics engineer and at the moment president of Morewood Design Labs.

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

“Mark and I assumed we’d construct a quick-and-dirty prototype, one thing they might get sensor knowledge from and use for creating software program. After which they’d go off to Asia and get it miniaturized there,” Casciola recollects. “However one revision led to a different.” Casciola ended up engaged on circuit designs for Fitbits nearly 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 just a little 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 up some consulting work. I had no thought Fitbit would turn into a family identify. I similar to engaged on something, whether or not I believe it’s a good suggestion or not, and even whether or not somebody is paying me or not.”

The earliest prototypes have been fairly massive, about 10 by 15 cm, Casciola says. They have been sufficiently big to simply hook as much as check gear, but sufficiently small to strap on to a prepared check 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 smooth 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 each day charging.

“Determining the appropriate steadiness of battery life, measurement, and functionality stored 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 a giant transfer: They turned away from the Bluetooth customary for wi-fi communications in favor of
the ANT protocol, a know-how developed by Garmin that used far much less energy. That meant the Fitbit wouldn’t be capable of add to computer systems instantly. As an alternative, 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 evaluation 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 how you can 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 customary 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. Someone truly mentioned 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 believe it added a stage of magic. You simply plopped your gadget on [the charger]. It seemed lovely, and it labored persistently.”

Many 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 at the least seven days’ value of collected knowledge.

The Fitbit was designed to withstand sweat, and so they typically survived showers and fast dips, says Friedman. “However sizzling tubs have been the bane of our existence. Folks clipped it to their swimsuits and forgot they’d it on once they jumped into the new tub.”

Fitbit’s demo or die second

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

Reside 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 depend would sync wirelessly to a laptop computer projecting to a display screen on stage. When Friedman hit refresh on the browser, the step depend would seem on the display screen. What might go incorrect?

Loads. Friedman explains: “You suppose counting steps is simple, however let’s say you do three steps. One, two, three. Whenever you carry your toes collectively, is {that a} step or is that the tip? It’s a lot simpler to depend 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 data its inaugural step depend. James Park

After a number of apply, the 2 thought they might 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 every little thing whereas I used to be nonetheless strolling. However the numbers confirmed up; I don’t suppose 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’ arms—or clipped onto their bras—by Christmas of 2008, they missed that deadline by a yr.

The algorithms that decide Fitbit’s depend

A part of Fitbit’s problem of getting from prototype to shippable product was software program improvement. They couldn’t count on customers to stroll as exactly as Park did for the demo. As an alternative, the gadget’s algorithms wanted to find out what a step was and what was a special form of movement—say, somebody scratching their nostril.

“Knowledge assortment was tough,” Park says. “Initially, it was a number of us carrying prototype units doing a wide range of totally different actions. Our head of analysis, Shelten Yuen, would comply with, videotaping so we might return and depend the precise variety of steps taken. We’d put on a number of units concurrently, to match the information 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 beauty of San Francisco is that no one appears to be like surprisingly at two guys tethered collectively strolling round speaking to themselves.”

“Older individuals are likely to have an irregular cadence—to the gadget, older individuals look quite a bit like buses going over potholes.”–James Park

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

Highway noise was one other large subject. “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 problem by in search of a daily cadence to depend steps, he provides, as a result of not everybody has a daily cadence. “Older individuals are likely to have an irregular cadence—to the gadget, older individuals look quite a bit like buses going over potholes.”

Fitbit’s founders enter the world of producing

A shopper gadget means mass manufacturing, doubtlessly in large portions. They talked to a number of contract-manufacturing companies, Park recollects. 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 along with the lowest-budget operations, as a result of they wanted an inexpensive stage of high quality.

“We noticed some fairly scary producers,” Park mentioned. “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 how you can 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. Once 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 pc. 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 might sync? And that turned out to be actually just some inches. In each different check we had performed, it was superb. It might 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 era 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 models from the manufacturing line are proven partially assembled [bottom]. James Park

“I assumed, if we might simply push that cable away from the antenna, we’d be okay,” Park mentioned. “The one factor I might discover in my resort room to try this was rest room paper. So I rolled up some rest room 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 era of Fitbits shipped.

Fitbit’s quick evolution

The corporate bought about 5,000 of these $99 first-generation models in 2009, and greater than 10 occasions that quantity in 2010. The rollout wasn’t totally easy. Casciola recollects that Fitbit’s logistics heart 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 with no reset button or a detachable battery. “Inevitably,” Casciola says, “firmware goes to crash. When you’ll be able to’t take the battery out, it’s important to have one other approach 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 can poke with a paper clip. Should you did this with the tracker sitting on the charger, it will reset. After all, we needed to have a approach for the tracker to see that sign. After 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.

“Should you clipped the tracker onto sweaty clothes—keep in mind, sweat has a excessive salt content material—a really tiny present would move,” 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 era of the Fitbit, known as the Fitbit One, Casciola added a brand new kind of chip, one which hadn’t been obtainable 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 energetic pin.

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

Chrome wasn’t an important alternative both. “It brought on issues with the charger interface,” Park provides. “We needed to do a number of work to forestall shorting there.”

They dropped the chrome after some tens of 1000’s of models 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 grew to become extensively obtainable as a brand new low-power communications customary, 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 should you had a current 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 fee of Bluetooth LE in cellphones; once 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, generally known 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’ need to higher monitor their sleep. The Fitbit’s algorithms allowed it to establish sleep patterns, a design alternative 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 supply apparent spots for attachment. So the Fitbit shipped with a skinny material wristband supposed to be used simply at evening. Customers started asking buyer assist if they might 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 depend. From 11 at evening 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 bought to assist most cancers analysis, have been abruptly in every single place. Different causes and actions jumped on the pattern with their very own brightly coloured wristbands. By early 2013, Fitbit, together with rivals Nike and Jawbone, had launched the Flex, a wrist-worn health tracker in roughly the identical model as these stylish 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 screen: It had no buttons and no display screen, simply 5 LEDs organized in a row and a vibrating motor. To alter modes, you tapped on the floor.

“We didn’t wish to change individuals’s watches,” Park says. The know-how wasn’t but able to “construct a compelling gadget—one which had a giant display screen and the compute energy to drive actually superb interactions on the wrist that may be worthy of that display screen. The know-how traits 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 screen. Customers managed it by tapping; 5 LEDs indicated progress towards a step depend chosen by way of an app [left]. iStock

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

The faucet a part of the interface, although, was “presumably one thing we didn’t get totally 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 vital, some customers couldn’t fairly intuit the appropriate solution to faucet.

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

And the remainder is historical past

In 2010, its first full yr in the marketplace, the Fitbit bought some 50,000 models. Fitbit gross sales peaked in 2015, with nearly 23 million units bought that yr, in accordance with
Statista. Since then, there’s been a little bit of a drop-off, as multifunctional good watches have come down in value and grown in recognition and Fitbit knockoffs entered the market. In 2021, Fitbit nonetheless boasted greater than 31 million energetic customers, in accordance with Market.us.Media. And Fitbit could now be using the pattern again to simplicity, as individuals discover themselves desirous to eliminate distractions and transfer again to easier units. I see this occurring in my family: 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 individuals to be energetic by electronically monitoring steps has had endurance.

“My father, who turned 80 on July 5, is fixated on his step depend,” Friedman says. “From 11 at evening 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?