Apple ditched 'unreliable' health sensors from its Watch

But a report now claims that, one-by-one, many of these sensors were dropped because they were unreliable or erratic.

Sources told The Wall Street Journal that the watch even became dubbed 'black hole' internally because it continued to suck in resources for four years.

The report added that Apple also struggled to find a purpose for the watch after the sensors were ditched, and were left 'wrestling with why a consumer would need or want such a device.'

Apple has not responded to MailOnline's request for comment.  

Apple is expected to launch the smartwatch in March with prices starting at $349, although a high-end 18-karat gold model could cost thousands of dollars.

Other sensors, such as detecting blood pressure and oxygen, were inconsistent and too complex and would have needed regulator approval.

However, Apple didn't remove all the sensors. 

On the back of the case, a ceramic cover with sapphire lens covers a sensor that uses infrared and visible-light LEDs and photodiodes to detect heart rate. 

Apple Watch will use this sensor, along with an accelerometer and the GPS and Wi‑Fi in a paired iPhone, to measure physical movement. 

This will work with the Watch's Activity app that can set Move goals, track exercise and make sure the wearer doesn't sit down for too long.

There will additionally be a Workout app to motivate wearers. 

Plus, developers will be able to create new apps with Apple's WatchKit.  

The more complex features may also be included in future models, said 'people familiar with the matter'.

Apple has asked its Asian suppliers to make 5-6 million units of its three Apple Watch models for the first-quarter, the Wall Street Journal reported, citing people familiar with the matter.

Taiwan-based Quanta Computer Inc, the sole assembler of the Apple Watch, started mass production earlier this year to get ready for an April launch, the Journal said.

Thousands will work round the clock during the Chinese New Year holidays at Quanta's factory in Changshu, China, the newspaper reported, quoting one person.

Analysts predicts sales of wearables will grow from 29 million in 2014 to 172 million in 2018, with a spike in 2015.

CCS Insight's latest forecast believes the most popular devices will be smartwatches and fitness trackers.

Ben Wood, CCS Insight's Chief of Research said: 'The Apple Watch will be instrumental in taking the wearables market to the next level of growth.

If successful, it'll create a rising tide that will lift the whole market.'

'If the Apple Watch performs as well as expected, its halo effect will result in a sales bonanza in the second half of 2015, with record-breaking shipments in the important fourth quarter.'

Last month, reports emerged that even without all these sensors, Apple's Watch will only last 19 hours on a full charge.

Apple fan site 9to5Mac said: 'For the first time, people with knowledge of the Apple Watch's development have provided us with the specific performance targets Apple wants to achieve for the Apple Watch battery, but the actual numbers may fall short of those targets.

'According to our sources, Apple opted to use a relatively powerful processor and high-quality screen for the Apple Watch, both of which contribute to significant power drain.'

It said Apple wanted the Watch to provide roughly 2.5 to 4 hours of active application use versus 19 hours of combined active/passive use, three days of standby time, or four days if left in a sleeping mode.

But, the site's sources said Apple will only likely achieve approximately two to three days in either the standby or low-power modes.

Last year, designers created an online demo of how apps may work on the Apple Watch. 

Created by Pipes, the interactive watch is modelled on official images released by Apple, and lets people see how their messages, emails and homescreen will look and work. 

The demo also shows how push notifications will appear, and lets users control music on the virtual watch. 

(dailymail.co.uk)