The Artist as Cardiologist: Rafael Lozano-Hemmer's 'Pulse Phone' App Monitors Your Ticker
Put simply, Pulse Phone is a heart rate monitor that gathers pulse data by using your iPhone's camera. As you lightly place your finger over the camera lens, the app registers subtle changes in the color and brightness of the image -- looking through your finger to monitor the blood as it pulses through your digits. This is made easier with the iPhone 4's built-in camera flash -- although older models will work (as will the newest iPod touch), provided that you're in a very well-lit room. "The nice thing about the flash is that it is so bright that you can easily use the app in complete darkness," Lozano-Hemmer tells us in an e-mail. "The results are also pretty immune to you moving your hand around while the pulse is being detected."
In the beginning, Apple refused to approve the app -- but it had nothing do with its status as a biometric analyzer. "We originally developed the app over a year and a half ago, but we had to hack into Apple's code for the camera," Lozano-Hemmer says. "So we were rejected." Since then, though, Apple loosened its restrictions and began allowing developers to dig in to the camera's coding. One Lozano-Hemmer and his team had unfettered access to the camera, they were able to develop their own algorithm that analyzes the user's pulse based on changes in the image's brightness and color.
We've seen heart rate apps before. Many of them rely on sound, much like stethoscopes, and haven't seen much success (Lozano-Hemmer is aghast that they would ask the user to put their pricey phone "right up to your sweaty chest"), while others require separate hardware. Lozano-Hemmer notes that there are other camera-based pulse apps on the market, but Pulse Phone allows the user to choose between quick readings and more accurate ones. ("We also think our image analysis is sturdier," he says.) For an app this simple, though, the results seem accurate enough to warrant the $1.99 price tag. Of course, the artist is quick to point out that Pulse Phone isn't a medical device, nor should it be used in place of FDA-certified heart rate sensors or a doctor's care.
But is Lozano-Hemmer really trying to get in to the medical device market, anyway? While Pulse Phone has an immediate usefulness, we're more interested in its potential for other 'Pulse' projects -- something that Lozano-Hemmer says will happen with future versions of the app. Imagine it as a mobile, biometric interface that allows you to remotely send your pulse data, say, to a city-wide installation, much like his 'Pulse Park' and 'Pulse Tank.' As with 'Vectorial Elevation,' which allowed people to design their own light sculptures online, future iterations of Pulse Phone will have the capacity to connect users through their own unique signatures.
Then again, biotech as art has long been an interest of Lozano-Hemmer's -- and he's not skimping on the research. We were skeptical that the iPhone's hardware could compete with bona fide medical devices but, apparently, it can. "The iPhone camera can totally differentiate between different wavelengths of light, so you could potentially use it to detect oxygen levels [as with a pulse oximeter]. The problem is with the light sources... ideally oximeters use a couple of light sources," he says, remarking that infrared clips and light shields could potentially turn the iPhone into a blood oxygen-measuring device. But perhaps that's for other developers to look into. Right now, he says, "we have to make some art!"