Apple's upcoming smartwatch is pegged for a fall release and will come in multiple designs, according to a new report in The Wall Street Journal. The device, widely dubbed the iWatch, is said to include over 10 sensors, with some dedicated to tracking users' health and fitness. Apple is planning to "address an overarching criticism of existing smartwatches that they fail to provide functions significantly different from that of a smartphone," according to one WSJ source.

Reuters reported yesterday that the smartwatch is likely to feature a 2.5-inch screen, wireless charging, and a heart sensor, with mass production starting next month for a release as soon as October. The WSJ, however, claims that the watch will come in multiple screen sizes. Reuters says Apple is set to ship 50 million units within a year of going on sale, and the WSJ believes there will be between 10 to 15 million shipments by the end of 2014.

Nikkei claimed earlier this month that Apple has collaborated with Nike for the smartwatch. Nike reportedly plans to wind down its FuelBand business and concentrate on software, having laid off much of its hardware team. Nikkei's report also said that the smartwatch will likely feature a curved OLED display, work with the new health-focused software in iOS 8, and launch in October.

"Watches are fashion accessories. One design doesn't fill all."

"I expect Apple to launch multiple smartwatches that come with different designs as watches are fashion accessories. One design doesn't fill all," says Ming-chi Kuo, the well-connected analyst at KGI Securities, in comments reported by the WSJ.

Apple's iPhone 5S already ships with an array of sensors including ambient light, proximity, an accelerometer, a gyroscope, a magnetometer, and the Touch ID fingerprint sensor. The phone also makes use of a "motion coprocessor," called the M7, that continuously collects data from the phone's sensors with minimal power draw. Any wearable device from Apple could work in a similar way to monitor steps, heart rate, and so on.

Apple has already expressed an interest in tracking and collating health data, announcing HealthKit for iOS 8 at its Worldwide Developers Conference earlier this month. The software allows third-party developers to feed data from their hardware into a single Health app so that users can get all their fitness information in one place; Apple did not, however, announce its own hardware to take advantage of this feature. A smartwatch with similar capabilities to the wealth of fitness devices on the market would be an obvious showcase for the new ability.