Printing An Air-Powered Integrated Circuit For Squishy Robots

October 15, 2025 by Maya Posch 10 Comments

There’s no rule that says that logic circuits must always use electrically conductive materials, which is why you can use water, air or even purely mechanical means to implement logic circuits. When it comes to [soiboi soft]’s squishy robots, it thus makes sense to turn the typical semiconductor control circuitry into an air-powered version as much as possible.

We previously featured the soft and squishy salamander robot that [soiboi] created using pneumatic muscles. While rather agile, it still has to drag a whole umbilical of pneumatic tubes along, with one tube per function. Most of the research is on microfluidics, but fortunately air is just a fluid that’s heavily challenged in the density department, allowing the designs to be adapted to create structures like gates and resistors.

A transistor or valve using a silicone membrane. (Credit: soiboi soft, YouTube)

Logically, a voltage potential or a pressure differential isn’t so different, and can be used in a similar way. A transistor for example is akin to the vacuum tube, which in British English is called a valve for good reason. Through creative use of a flexible silicone membrane and rigid channels, pulling a vacuum in the ‘gate’ channel allows flow through the other two channels.

Similarly, a ‘resistor’ is simply a narrowing of a channel, thus resisting flow. The main difference compared to the microfluidics versions is everything is a much larger scale. This does make it printable on a standard FDM printer, which is a major benefit.

Quantifying these pneumatic resistors took a bit of work, using a pressure sensor to determine their impact, but after that the first pneumatic logic circuits could be designed. The resistors are useful here as pull-downs, to ensure that any charge (air) is removed, while not impeding activation.

The design, as shown in the top image, is a 5-stage ring oscillator that provides locomotion to a set of five pneumatic muscles. As demonstrated at the end of video, this design allows for the entire walking motion to be powered using a single input of compressed air, not unlike the semiconductor equivalent running off a battery.

While the somewhat bulky nature of pneumatic logic prevents it from implementing very complex logic, using it for implementing something as predictable as a walking pattern as demonstrated seems like an ideal use case. When it comes to making these squishy robots stand-alone, it likely can reduce the overall bulk of the package, not to mention the power usage. We are looking forward to how [soiboi]’s squishy robots develop and integrate these pneumatic circuits.

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Behold Self-Synchronizing, Air-Flopping Limbs That Hop And Swim

May 23, 2025 by Donald Papp 6 Comments

Dutch research institute [AMOLF] shows off a small robot capable of walking, hopping, and swimming without any separate control system. The limbs synchronize thanks to the physical interplay between the robot’s design and its environment. There are some great videos on that project page, so be sure to check it out.

A kinked soft tube oscillates when supplied with continuous air.

Powered by a continuous stream of air blown into soft, kinked tubular limbs, the legs oscillate much like the eye-catching “tube man” many of us have seen by roadsides. At first it’s chaotic, but the movements rapidly synchronize into a meaningful rhythm that self-synchronizes and adapts. On land, the robot does a sort of hopping gait. In water, it becomes a paddling motion. The result in both cases is a fast little robot that does it all without any actual control system, relying on physics.

You can watch it in action in the video, embedded below. The full article “Physical synchronization of soft self-oscillating limbs for fast and autonomous locomotion” is also available.

Gait control is typically a nontrivial problem in robotics, but it doesn’t necessarily require a separate control system. Things like BEAM robotics and even the humble bristlebot demonstrate the ability for relatively complex behavior and locomotion to result from nothing more than the careful arrangement of otherwise simple elements.

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Supercon 2023: Soft Actuators As Assistive Tech

August 21, 2024 by Tom Nardi 1 Comment

When we think of assistive prostheses or braces, we often think of hard and rigid contraptions. After all, it wasn’t that long ago that prosthetic limbs were still being made out of wood. Even devices made of more modern materials tend to have a robotic quality that inevitably limits their dexterity. However, advancements in soft robotics could allow for assistive devices that more closely mimic their organic counterparts.

At Supercon 2023, Benedetta Lia Mandelli and Emilio Sordi presented their work in developing soft actuator orthosis — specifically, a brace that can help tetraplegics with limited finger and thumb control. Individuals with certain spinal cord injuries can move their arms and wrists but are unable to grasp objects.

Existing braces can help restore this ability, but they are heavy and limited by the fact that the wearer needs to hold their wrist in a specific position to keep pressure on the mechanism. By replacing the rigid linkage used in the traditional orthosis, the experience of using the device is improved in many ways.

Not only is it lighter and more comfortable to wear, but the grip strength can also be more easily adjusted. The most important advancement however is how the user operates the device.

Like the more traditional designs, the wearer controls the grip through the position of their wrist. But the key difference with the soft actuator version is that the user doesn’t need to maintain that wrist position to keep the grip engaged. Once the inertial measurement units (IMUs) have detected the user has put their wrist into the proper position, the electronics maintain the pressure inside the actuator until commanded otherwise. This means that the user can freely move their wrist after gripping an object without inadvertently dropping it.

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On the left, a transluscent yellowy-tan android head with eyes set behind holes in the face. On the right, a bright pink circle with small green eyes. It is manipulated into the image of a smiling face via its topography.

A Robot Face With Human Skin

July 25, 2024 by Navarre Bartz 30 Comments

Many scifi robots have taken the form of their creators. In the increasingly blurry space between the biological and the mechanical, researchers have found a way to affix human skin to robot faces. [via NewScientist]

Previous attempts at affixing skin equivalent, “a living skin model composed of cells and extracellular matrix,” to robots worked, even on moving parts like fingers, but typically relied on protrusions that impinged on range of motion and aesthetic concerns, which are pretty high on the list for robots designed to predominantly interact with humans. Inspired by skin ligaments, the researchers have developed “perforation-type anchors” that use v-shaped holes in the underlying 3D printed surface to keep the skin equivalent taut and pliable like the real thing.

The researchers then designed a face that took advantage of the attachment method to allow their robot to have a convincing smile. Combined with other research, robots might soon have skin with touch, sweat, and self-repair capabilities like Data’s partial transformation in Star Trek: First Contact.

We wonder what this extremely realistic humanoid hand might look like with this skin on the outside. Of course that raises the question of if we even need humanoid robots? If you want something less uncanny, maybe try animating your stuffed animals with this robotic skin instead?

Soft Robotic System For In Situ 3D Bioprinting And Endoscopic Surgery

April 20, 2023 by Maya Posch 8 Comments

The progress of medical science has meant increasingly more sophisticated ways to inspect and repair the body, with a shift towards ever less invasive and more effective technologies. An exciting new field is that of in situ tissue replacement in a patient, which can be singular cells or even 3D printed tissues. This in vitro approach of culturing replacement tissues comes however with its share of issues, such as the need for a bioreactor. A more straightforward approach is printing the cells in vivo, meaning directly inside the patient’s body, as demonstrated by a team at the University of New South Wales Sydney with a soft robot that can print layers of living cells inside for example a GI tract.

In their paper, the team — led by [Dr Thanh Nho Do] and PhD student [Mai Thanh Thai] — describe the soft robot that is akin to a standard endoscope, but with a special head that has four soft microtubule artificial muscles (SMAM) for three degrees of freedom and fabric bellow actuators (FBA) that provide the motion desired by the remote controller. The system is configured in such a way that the operator inputs the rough intended motions, which are then smoothed by the software before the hydraulics actuate the head.

In a test on a simulated GI tract, the researchers were able to manipulate a prototype, and deposit a range of materials from the installed syringes. They envision that a system like this could be used as with endoscopes and laparoscopy to not only accurately deposit replacement cells inside the patient’s body, but also to perform a range of other surgical interventions, whereby the surgeon is supported by the system’s software, rather than manipulating the instruments directly.

Complex Movements From Simple Inflatables, Thanks To Physics

July 24, 2022 by Donald Papp 5 Comments

Inflatable actuators that change shape based on injected pressure can be strong, but their big limitation is that they always deform in the same way.

The Kresling pattern, which inspired the actuator design.

But by taking structural inspiration from origami, researchers created 3D-printed actuators that show it is possible to get complex movements from actuators fed by only a single source of pressure. How is this done? By making the actuators physically bi-stable, in a way that doesn’t require additional sources of pressure.

The key is a modified design based on the Kresling pattern, with each actuator having a specially-designed section (the colored triangles in the image above) that are designed to pop out under a certain amount of positive pressure, and remain stable after it has done so. This section holds its shape until a certain amount of negative pressure is applied, and the section pops back in.

Whether or not this section is popped out changes the actuator’s shape, therefore changing the way it deforms. This makes a simple actuator bi-stable and capable of different movements, using only a single pressure source. Stack up a bunch of these actuators, and with careful pressure control, complex movements become possible. See it in action in two short videos, embedded just below the page break.

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Can Robots Give Good Hugs?

January 24, 2022 by Kristina Panos 29 Comments

We could all use a hug once in a while. Most people would probably say the shared warmth is nice, and the squishiness of another living, breathing meatbag is pretty comforting. Hugs even have health benefits.

But maybe you’re new in town and don’t know anyone yet, or you’ve outlived all your friends and family. Or maybe you just don’t look like the kind of person who goes for hugs, and therefore you don’t get enough embraces. Nearly everyone needs and want hugs, whether they’re great, good, or just average.

So what makes a good hug, anyway? It’s a bit like a handshake. It should be warm and dry, with a firmness appropriate to the situation. Ideally, you’re both done at the same time and things don’t get awkward. Could a robot possibly check all of these boxes? That’s the idea behind HuggieBot, the haphazardly humanoid invention of Katherine J. Kuchenbecker and team at the Max Planck Institute for Intelligent Systems in Stuttgart, Germany (translated). User feedback helped the team get their arms around the problem.

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