SlimeVR Opens Crowdfunding for Its Long-Life, Rapid-Update Butterfly Body Tracking Sensors

Full-body tracking specialist SlimeVR has officially opened crowdfunding for its open source Butterfly trackers, eight months after unveiling the hardware and releasing its design files.

"Based on the success and experience of SlimeVR Full-Body Trackers, SlimeVR Butterfly Trackers push the limits of comfort and ease of use for body trackers in virtual reality, motion capture, streaming, and more," the SlimeVR team writes of the next-generation trackers.

"Like the original version, these new SlimeVR Butterfly Trackers are open hardware sensors with open-source software that track the movement of your body. They do not require base stations, can’t be occluded, are completely wireless, and last for days on a single charge. Now, with the brand-new, unique, ultra-light split design inspired by butterflies, they are less than 7mm [around 0.28"] thick and weigh less than 10 grams [around 0.02lbs], making them the most comfortable solution for full-body tracking on the market today."

SlimeVR announced the Butterfly back in June last year as a follow-up to the original Espressif ESP8266-based sensors and the later Nordic Semi nRF52840-powered Smol Slime. The Butterfly is so-named owing to a shift to a two-part split design, with the thickness reduced by putting the hardware in two separate housings connected by a small flexible hinge — designed to boost comfort over the thicker, rigid single-piece designs of its predecessors.

With the crowdfunding campaign now live the SlimeVR team has confirmed 48-hour-plus battery life, full 360-degree coverage with a 1–5cm precision and sub-15ms latency, and a target of 100–200Hz update frequencies — above the 100–140Hz it was promising last year, which was itself a big upgrade over the SlimeVR v1.2's 100MHz. Pricing has been set at $279 for the "Core Set Bundle" capable of tracking the position and rotation of the wearer's hips, knees, and chest, as well as the position of their feet, rising to $364 for the "Enhanced Core Set" that adds feet rotation tracking, while the $449 "Full Body Set Bundle" includes 10 trackers to add full position and rotation tracking of the user's elbows.

If that's still not enough, the "Motion Capture Set Bundle" uses a whopping 17 trackers to track the position and rotation of the wearer's chest, waist, knees, ankles, feet, upper and lower arms as distinct body parts, shoulders, hands, and head, plus 20 iron-on patches designed for visual tracking of a motion capture suit. Finally, $499 gets a pink version of the "Full Body Set" with bonus charging dock.

Interested parties can back the campaign on Crowd Supply, with hardware expected to ship by the end of August 2026; as before, hardware design files and source code are available in the project's GitHub repository under the permissive MIT and Apache 2.0 licenses.