Philips Hue and other smart bulbs based on the Zigbee standard could soon act as motion sensors without the need for any additional hardware. This would mean they could automatically switch on when someone enters a room without using a separate motion sensor.Even better, the new functionality looks set to be added to existing Hue bulbs through an update to the Hue Bridge Like many of you, I currently use motion sensors to automatically switch on some Philips Hue bulbs and light strips, or to activate scenes. My kitchen and bathroom lights both come on automatically when someone walks into the room, for example, and switch off again if no movement is detected for two minutes.But a new approach to motion sensing could render the additional hardware unnecessary. The bulbs themselves look set to gain the necessary smarts to sense motion on their own.The secret is technology which can detect the interference in radio signals created by someone walking into a room. This interference can then be used as a trigger to control the light bulbs in the same way as existing motion sensors.One version of this, known as Sensify, was developed by wireless networking company Ivani. Another was developed by the Connectivity Standards Alliance the industry group responsible for Zigbee which it calls Ambient Sensing.Because it relies on interference in the radio signals between devices, you do need multiple Zigbee devices in a room for it to work.For Sensify on Zigbee, these detection areas consist of the area contained within a group of 3-4 devices. These detection areas effectively create virtual sensors within the network, providing occupancy data that can be used for a wide range of functionalities.For instance, several Zigbee devices grouped in one room can provide room-level data granularity for occupancy data.Ivani says its partner companies can also use this type of motion sensing for smart security products.Convenience triggers are suitable for a quick response application such as turning lights on when entering a room. These have a typical average response time of less than 500ms, with 90% of triggers occurring within 1 second of entering a detection area.Security triggers are suitable for a high confidence application such as home security. These have an average typical response time in the range of a few seconds; however, an extremely low false positive rate of less than 1 false positive every 6 months is typical. Both outputs can operate simultaneously on the same underlying data, providing customers with occupancy data for multiple use cases (e.g. turning on their lights and protecting their property) at the same time from the same device.Any Zigbee devices can be upgraded to add the tech, which includes Philips Hue lights.Ivani hasnt confirmed the names of any of its partners, but did tell The Verge that there are tens of millions of devices ready to be activated.The best part is that it can work on devices already in most homes. There are tens of millions of devices with the base firmware already out there; were just working on the final touches to light up the full experience, Ivani cofounder Justin McKinney tells The Verge.An obvious use case for this is a Zigbee-based smart lighting system such as Philips Hue. Theres been speculation that Hue is working on a Zigbee sensing technology since its sister company Wiz debuted a similar tech called SpaceSense in 2022, which uses WNS over Wi-Fi. The well-informed hueblog.com reports that Zigbee wireless network sensing is the technology Hue will most likely use.According to HueBlog which first got wind of this more than a year ago Philips may be going with Zigbee Ambient Sensing.Now there seems to be movement in the story, as Zigbee Ambient Sensing is precisely the building block on which the new function is likely to be based.According to the information available to me, the Philips Hue function requires at least three light sources in a room, which must be placed at a certain distance and in a suitable shape. A permanent power supply to the light sources is of course essential. It should also be possible to set the intensity of the motion detection.No timings are yet known, but it does sound like we may not have too long to wait.Image: CSAAdd 9to5Mac to your Google News feed. FTC: We use income earning auto affiliate links. More.Youre reading 9to5Mac experts who break news about Apple and its surrounding ecosystem, day after day. Be sure to check out our homepage for all the latest news, and follow 9to5Mac on Twitter, Facebook, and LinkedIn to stay in the loop. Dont know where to start? Check out our exclusive stories, reviews, how-tos, and subscribe to our YouTube channel