The Nexus Hand from COVVI is not a typical first-generation bionic hand. Led by proven industry veterans, COVVI’S team seems to have made key improvements to current mainstream designs.
What’s On This Page?
- A Quick Look at the Nexus Hand
- Grip Patterns & Control System
- Thumb Rotation
- Proportional Speed Control
- Auto Grip
- Sensory Feedback
- Wrist Design
- Lift Capacity & Grip Strength
- Water and Dust Resistance
- Glove Options
- User Software
- Suitability for Above-the-Elbow Solutions
- User Feedback Survey & Results
- Considerations Before Buying a Nexus Hand
- Related Information
A Quick Look at the Nexus Hand
As is the case with most new bionic companies/products, not many substantive videos have been made of the Nexus Hand. This is the most descriptive one that we could find:
Of particular interest are some of its innovative grip switching features and also the manufacturer’s emphasis on durability. More about these features in the relevant sections below.
Nexus Hand’s Key Features
Grip Patterns & Control System
Similar to most bionic hands currently on the market, the Nexus utilizes a myoelectric control system. That is, myoelectric sensors placed against the skin of the residual limb detect muscle movements. A control system then translates these movements into commands for the bionic hand, typically to open or close the hand. Exactly which fingers open or close depends on the selected grip.
The Nexus currently offers 14 possible grips divided into two groups based on whether the thumb is positioned to oppose the fingers or to run parallel alongside them. The hand can support up to 24 different grips but neither of these numbers is that meaningful because most users only use a few grips. Most use one grip 70 % of the time. So, the real key to grip effectiveness is how quickly and easily users can switch between their core grips.
This is an area where Nexus excels. As with most bionic hands, it allows users to rotate through all available grips by triggering two open commands in succession or what’s called a co-contraction, where the use clenches the open and close muscles simultaneously. But selecting a grip this way can be slow and cumbersome, so Nexus also allows users to switch to specific grips by pressing force sensors in individual fingertips. Users can assign specific grips to each force sensor via a mobile app.
We think that this is a really smart way to allow users to change grips because it’s quick, convenient, and addresses the vast majority of grip needs.
As a true component hand (i.e. a bionic hand that can be used as a component of a broader bionic arm solution), Nexus can also be controlled using modern pattern recognition systems like Coapt’s Gen2 and, before long, IBT’s Sense. This allows Nexus to offer even more sophisticated and intuitive control.
Nexus provides powered rotation of its thumb so that it either opposes the fingers or lies parallel to them. This can occur dynamically as part of the grip selection and open/close process. Alternatively, the user can manually trigger a powered repositioning of the thumb by tapping a rocker switch positioned at the thumb’s base.
This mechanism is a perfect example of COVVI’S design experience. Allowing the user to manually reposition a thumb sounds like an easy task but it is more complicated than it appears. If the force required to move the thumb is too great, attempting to move it may rotate the wrist instead. If the required force is too small, the thumb may get easily bumped into the wrong position.
Having the thumb motor take care of the repositioning, even when that repositioning is triggered manually, is an ideal solution.
Proportional Speed Control
Proportional speed control refers to the ability of users to control the speed and force of a bionic hand’s grip by increasing or decreasing the speed/strength of the muscle movement needed to trigger a close signal.
The Nexus Hand not only offers this feature; it also supports improved control through feedback from pressure sensors embedded in the hand’s fingertips (see the section on Sensory Feedback below).
Nexus offers an auto-grip feature that users can enable or disable. When enabled, the hand will apply a small continuous force when it detects that an object is beginning to slip from its grasp.
Nexus also offers an auto-relax feature. When enabled, the thumb and fingers will slowly revert to the open position after 30 seconds.
Both these features are disabled by default because they consume power.
The Nexus Hand can provide sensory feedback thanks to pressure sensors in its fingertips. However, it is up to the designer of the socket (or bionic elbow) to convey this feedback to users via vibration or some other mechanism.
The Nexus has a built-in flex wrist with a range of motion of plus/minus 30 degrees of flexion/extension. This can operate either in a passive flex mode or can be locked into one of three positions at 0, plus 30, or minus 30 degrees.
The system also comes with the industry-standard Electric Quick Disconnect (EQD) wrist connector.
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Lift Capacity & Grip Strength
The Nexus offers a maximum finger load limit of 16 kilograms and a maximum hand load limit of 90 kg at the knuckles (i.e. the ability to push oneself up using a closed fist for support).
Nexus’s grip force depends on the selected grip, ranging from 22 newtons for its Key Grip to 80 newtons for its Power Grip. This should be sufficient for most daily tasks.
The Nexus Hand has several features focused on durability.
First, the thumb and fingers have been made entirely from a combination of stainless steel and aluminum. Second, they all have a passive flexing capability to prevent breakage if the hand is dropped or struck from the back.
Even the design of the Nexus glove is heavily focused on durability, with rigid covers holding the glove in place and protecting it.
That having been said, the Nexus is not designed for use in impact sports of any kind, and must not be used in any sport that would cause the hand to get wet.
Water and Dust Resistance
The Nexus has an official IP rating of 44, which means that it offers protection against solid objects that are over 1mm and against water splashing from any angle.
This does not qualify the Nexus as either waterproof or dustproof. It should therefore only be used in relatively clean, dry environments.
Nexus gloves, which they call “hand covers”, are made from medical grade silicone. They are highly water-resistant and come in four colors.
Use of the glove is not optional — it is an integral part of the Nexus’s design. Indeed, it is not really a glove in the traditional sense. Think of it as a flexible, replaceable part of the hand’s outer shell that is designed to be held in place and protected by rigid covers.
The Nexus offers a flexible battery solution that will follow the contours of the limb. It is charged via a waterproof USB-C.
We do not have any specific information on how long the battery lasts or how long it takes to charge once fully depleted. However, we have been assured that the battery will last a full day for typical use.
As with most bionic hands, the battery should be recharged each night.
COVVI offers a software application called the COVVI Go App, which works on both IOS and Android tablets and smartphones.
This app is used by the prosthetist to configure the Nexus Hand…
…and also by the end-user to adjust the configuration and view the hand’s status:
It is beyond the scope of this article to review the app in full. Our only observation is that it seems to be both comprehensive and professionally designed — yet another sign that COVVI’s experienced team is producing a notably mature startup product.
Suitability for Above-the-Elbow Solutions
The Nexus can be used as the hand component in above-the-elbow solutions. As long as the master control system (i.e. either an electric elbow or a pattern recognition system) sends the appropriate control signals, Nexus will respond accordingly.
According to our information, the Nexus sells for between $20,000 and $30,000 US for a typical below-the-elbow solution, including all prosthetist fees.
For a complete list of prices for other bionic hands, please see our Bionic Hand Price List.
The Nexus Hand offers a two-year limited warranty. Users can also purchase extended warranties of 12, 24, or 36 months, which can be purchased at any time before the expiry of the initial warranty.
User Feedback Survey & Results
Are you currently using the Nexus Hand or have you used it in the past?
If so, why not help others by sharing your experiences in this quick survey:
We do not yet have a sufficient number of survey participants to publish fair and accurate results for the Nexus Hand.
As soon as we do, we’ll update this section.
Considerations Before Buying the Nexus Hand
The extensive backgrounds of COVVI’S management, design, and engineering personnel give us confidence that the Nexus Hand will avoid many of the early flaws one might expect from a startup with a less experienced team.
However, because the Nexus is a new device, we don’t yet have any independent user feedback to validate this confidence.
We’ll update this section as soon as we do.
For a list of competitor devices, see All Bionic Hands.
For a comprehensive description of all current upper-limb technologies, devices, and research, see our complete guide.
If you are shopping for a bionic hand, do not miss our article on Bionic Hand Control Systems. Getting this part of your bionic system right is probably the biggest single ingredient in your long-term satisfaction.
Click here for more information on COVVI.