Grippy Bionic Hand - Bionics For Everyone

Grippy is one of the more interesting startup bionic hands that we’ve reviewed, especially its fully adaptive grip and low price.

What’s On This Page?

A Quick Look at Grippy

The following video is a bit lengthy (18 minutes) but provides a detailed look at Grippy:

As you can see from this video, Grippy has several compelling features including:

A fully adaptive grip that automatically conforms to the shape of whatever object is being grasped.
The use of MMG (Mechanomyogram) sensors for user control instead of more traditional myoelectric (EMG) sensors. MMG sensors monitor the mechanical signal generated by a muscle when it contracts instead of the electrical signal detected by EMG sensors.
Sensor optimization technology to prevent the hand from accidentally opening when carrying an object.
A sense of touch using vibration feedback.

Let’s examine these and other features in more detail.

Key Features

Grip Patterns & Control System

As mentioned, Grippy uses a fully adaptive grip where the hand’s digits automatically wrap around an object to conform to that object’s shape.

Other hands also use adaptive grips, mainly through a method of finger stalling, i.e. each finger involved in a grip pattern continues to close until it encounters resistance. But this feature is merely intended to augment the grip pattern that has been explicitly selected by the user.

Similar to Adam’s Hand, Grippy uses its adaptive grip as its primary means of grasping objects. Users do not have to switch grips before grasping an object. They merely position the hand and trigger the close command, letting the hand and its software do the rest. Here are a few examples:

There are multiple advantages to this approach:

no grip switching;
faster, more intuitive use;
eliminates the need for a more expensive pattern recognition control system, as a simple two-channel system should suffice.

However, there are a few unique challenges to this approach, including:

How do you use the hand when no grasping action is required, such as pressing the keys on a keyboard? The answer here is that you simply obstruct the digits you require while letting the rest of the digits close. For example, to type on a keyboard, simply obstruct the forefinger while closing the hand. This will leave the forefinger extended for one-finger typing.
How do you operate something like a power drill, where you have to maintain a grip with most digits but still allow the trigger finger to open and close as necessary? This is not currently possible with Grippy. For a unilateral amputee, the best option is to use the other hand.

Finally, Grippy uses Mechanomyogram (MMG) sensors versus traditional myoelectric (EMG) sensors to facilitate user control. Why? That’s exactly what we asked Robo Bionics, and their answer was impressive:

“We wanted Grippy to be used equally by someone who doesn’t have a hand due to traumatic loss as well as someone without their hand from birth (congenital), in case of the congenital cases they were not able to achieve fine control of muscles as they had never learned it. The same issue was also faced by people who underwent traumatic amputations and were using body-powered, cosmetic, or no prosthesis for over 5 years after amputation. EMG for all these cases needed extensive training time and during the training sessions, the misfiring of the sensors would also demotivate the users. EMG readings were also affected due to humidity and heat which caused a lot of sweating in most places in India. We mitigated all those problems with the use of MMG and it brought our training period down to 15 to 20 minutes, even in trials with above elbow amputation cases.”
Llewellyn D’sa, Co-Founder & CEO, Robo Bionics

An additional explanation is provided from 10:33 to 11:27 of the preceding video.

This is why we love tracking down bionic limbs from all over the world and at different stages of development. The level of innovation that we routinely encounter is, quite frankly, both astounding and humbling.

Thumb Rotation

Grippy’s thumb occupies two possible positions:

The thumb opposes the index and middle fingers for a cylindrical grip.
The thumb opposes the little finger for a better spherical grip.

Grippy will automatically position the thumb depending on the shape of the object that it is trying to grasp. The user does not have to explicitly control this.

Proportional Speed Control

Embarrassingly, we forgot to ask this question in our initial discussions with Robo Bionics. We have submitted it as a follow-up question and will update this section as soon as we receive a reply.

Auto-Grip

Grippy does have an auto-grip capability. That is, it can sense that an object is slipping from its grasp and automatically tighten its grip to compensate. However, this feature may not work properly if the battery is critically low.

Grippy also uses a sensor optimization technology to prevent accidentally dropping grasped objects. If the hand is gripping an object, it will not release that object while the hand is in motion. The hand’s motion must first stabilize before the user can open it.

Sensory Feedback

Grippy provides sensory feedback via three vibrators. When closing the grip, the three sensors fire in succession. When opening the grip, these sensors fire in reverse order. When grasping an object, just one of the vibrators fires. It provides rapid vibrations for a soft object and prolonged vibrations for a hard object.

This strikes us as a very innovative and intuitive use of these vibrators.

Wrist Design

Grippy is currently limited to a fixed wrist system owing to its incorporation of a cooling system. It is not yet compatible with other wrist options. However, Robo Bionics is working to either develop a movable wrist on its own or to make Grippy compatible with another wrist already on the market.

Size & Weight

Grippy weighs 250 grams for the hand and 90 grams for the battery. A custom socket is likely to weigh between 400 to 450 grams for a total weight of roughly 800 grams.

Currently, Grippy is only made in one adult size for users who are aged 15 and above. Robo Bionics can make a larger hand, if necessary, but it cannot currently go smaller than this.

Lift Capacity & Grip Strength

Grippy can carry up to two kilograms.

It can also exert up to 20 Newtons of pressure per finger with a maximum carrying capacity for the hand of 6 kilograms when using the hook grip. This is equivalent to roughly 60 Newtons of force.

By comparison, the average maximum grip force for women is 292 Newtons, and, for men, 517 Newtons. The average grip force used in daily activities is 70 Newtons.

Durability

We rely mostly on feedback from our User Satisfaction Survey as our main measure of durability. However, Grippy is new to us (and therefore to our audience), so it may be a year or two before we have sufficient feedback to publish this information.

In the absence of this feedback, we rely on warranty information, which you can see in its own section below.

Water and Dust Resistance

We do not yet have an official IP rating for Grippy, but we do know from its user manual that it should only be used in dry conditions, i.e. it should not be exposed to water in any form.

We do not yet have any information on its resistance to dust.

Glove Options

Robo Bionics offers one type of glove for Grippy: a removable, washable cotton glove with silicon fingertips. The glove comes in a single skin shade:

These gloves typically last between 3 to 6 months if washed and maintained properly. The user can replace the glove without the assistance of a prosthetist.

Robo Bionics sells a set of 5 gloves separately for $100 US.

Batteries

Grippy uses a 12-watt lithium-ion battery that provides 8 to 10 hours of typical use.

The system comes with a battery charger and requires up to five hours to charge the battery if it is completely drained.

User Software

A software tool is provided to prosthetists if they want to change the sensitivity of the sensors based on the muscle strength of the user. Prosthetists can also update the firmware of the device.

However, there is no software for the end user at this time.

Suitability for Above-the-Elbow Solutions

Grippy is not yet suitable for above-the-elbow bionic solutions. There is no reason that the hand itself can’t be used in such a solution but Robo Bionics wants to resolve its wrist options before advertising this capability.

Suitability for Children

As mentioned, Grippy comes in only one size, which is set as a unisex size for adult men and women. It is therefore not suitable for children.

Price

Grippy will eventually sell for $10,000 to $20,000 US in the United States for a complete below-the-elbow solution. It is much less expensive outside of the U.S., selling in India for less than $5,000 US.

As mentioned, a set of 5 replacement gloves costs $100 US, which should last for about 2 years.

For a complete list of prices for other bionic hands, please see our Bionic Hand Price List.

Availability

Grippy is currently available only in India. However, Robo Bionics does have plans to launch it in the U.S. once they have obtained FDA approval.

Warranty

Robo Bionics offers a 1-year warranty on Grippy, which users can pay to extend by an additional year.

They also offer a 6-month warranty on accessories.

User Feedback Survey & Results

Survey

Are you currently using Grippy or have you used it in the past?

If so, why not help others by sharing your experiences in this quick survey:

Results

We do not yet have a sufficient number of survey participants to publish fair and accurate results for Grippy. As soon as we do, we’ll update this section.

Considerations Before Buying a Grippy

As with any bionic hand that is new to the market, the first consideration before buying a Grippy is a lack of track record. Until a bionic hand is on the market for a while, there is simply no way to independently assess its long-term performance or durability.

That having been said, Grippy’s combination of advanced features and low price is compelling, especially in markets where most users cannot afford so-called “name brand” bionic hands that have been on the market for many years.

I would also like to note that Grippy’s manufacturer, Robo Bionics, has been extremely open and transparent with us, which we always view as a very positive sign.

The best plan is probably to find a good prosthetist who will let you take Grippy for a test run, preferably in your own home for a week or two.

For a list of competitor devices, see current options for bionic hands.

For a comprehensive description of all current upper-limb technologies, devices, and research, see our complete guide.

Click here for more information on Robo Bionics.