The next wave of factories more closely resembles bird-wings than modern machines

Introducing Compliant Mechanisms

Isabella Grandic
Jan 2 · 9 min read

What do spaceship release parts, surgical robots and tools have in common?

They require us to build “things” that (most of the time) “move” or have the ability to “move things.” (AKA we’re dealing with mechanisms).

While software is taking over the world, we haven’t yet experienced the same takeover for physical items. (Don’t get me wrong, I hope software continues taking more substantial bites out of our world. The point I’m making is we haven’t seen the same level of innovation with hardware).

Since we don’t have fully immersive VR (yet!), all of us are stuck living in the real world. We interact with mechanisms all the time! I’m writing this on the Toronto Subway, which has wheels, gears, pulleys, etc. Without tools, the doors wouldn’t open to let me in; the subway wouldn’t be able to move, etc.

Mechanisms make our non-human items move. They’ll become essential assets in spacecraft creation; they’ll make tumour-suppressing surgical robots and some cool chainsaws.

Today, the way we use mechanisms is pretty saturated. The first thing that comes to mind is probably transportation. We would still be riding on horses if it wasn’t for movable machinery. Energy is another big one. The fact that we have steam engines is a mechanical invention. Manufacturing, as well.

But what about furniture? Clothing? Healthcare (to an extent)? Construction? The world we live in is pretty stagnant. Besides robotic furniture companies like Ori, most of our everyday items have one state of equilibrium. What if that was two? Three? Your room could be a bedroom by night, office by day, and a salsa-dance-studio whenever you feel like it 💃.

Part of the reason many industries and items have been less impacted by industrialization is that the approach we’re using isn’t universal. When you think about machinery, you probably imagine a collection of gears working together — or a bunch of metal working together. You wouldn’t be very wrong. We design a lot of our machinery that way. I don’t know about you, but I don’t want my bedroom looking like the inside of a factory.

But there’s good news. The way we make products is drastically changing, along with our ability to make things move. In the next coming years, the way you interact with physical items will completely change, introducing momentum to previously unimaginable scenarios. And the culprit? Compliant mechanisms.

A new type of movement: machines that bend

🥁Introducing 🥁: compliant mechanisms. In short, they have flexible corners (flexures), instead of hinges connecting two rigid parts. They create motion through elastic deformation (flexible parts)

Some terminology:

  • Fully compliant = the entire system is made of flexures
  • Partially compliant = some of the system is compliant, some of it is rigid
  • Monolithic = system made from one “part.”
  • Deformation = how something behaves in response to a load (e.g., when you put 10 pounds on a table, the table will stay intact).

Just for fun, some compliant mechanism gifs 🤩:

The inspiration behind their design is natural systems. Think about your body. How many bolts did mother nature place in you? None. Compliant systems dominate the body (e.g., your heart, hands… everything that moves). Nature has been using elasticity to run things for a very very long time. Compliance is not “new.”

However, traditionally it has been challenging to implement for reasons beyond the scope of this blog post. Short version: how elastic structures react to loads is less predictable; accurate design is exponentially harder.

Compliant mechanisms are in you!!!

What makes compliant mechanisms exciting is its potential properties. Because they use fewer parts (e.g., two connected parts become one), we now:

  • Simplify manufacturing (therefore it’s cheaper)
  • Decrease size (less chunky metal pieces holding something together
  • Decrease weight + increase portability
  • Preciser motion (fewer systems relying on each other = more predictability)
  • Less friction and wear (longer-lasting!!)

We can make parts that are: cheaper, smaller, simpler, preciser and longer-lasting. No matter what your business/industry is, at least one of these properties could be exciting.

WOOOOOO!

Space: Lighter, cheaper space parts? Sign me up!!! It costs $27,000 per pound to send stuff into space (+ cost to manufacture). If parts were lighter, we could send more supplies for the same cost of launching.

Surgery: precision = more accuracy (obviously). If a neurosurgeon had the option between more accurate and less accurate devices, they’d choose accuracy any day. Because of their increased simplicity, compliant mechanisms are more accurate than their non-compliant counterparts.

Emergency Services: more portable health supplies!! There’s a specific kind of compliant mechanism called a lamina emergent mechanism (LEM). It is a 2D surface that can become 3D (like one of those fun birthday pop-up cards). This lets us build more compact devices, which we can use in emergencies. E.g., blood lancets, inhalers, scalpels.

Improved solar capture: using LEMs, we can take an array of solar cells, and allow it to have many positions (many states of equilibrium). Depending on where the sun is, the solar cells could reposition themselves.

Cheap Monitoring/Cleaning: devices can be made small (micro, even nano level), and are cheap. They can be used to clean traditionally hard to reach surfaces (e.g., industrial pipes, our bloodstreams, etc.). We can increase the lifespan of our buildings and ourselves!!

With such an exquisite menu of options, there’s hardly a shortage of implications. Compliant mechanisms almost seemed too good to be true, so I tried to make them myself. 🤓

3D printing my own Compliant Mechanisms

If you google “compliant mechanisms,” you’ll quickly learn that BYU (Brigham Young University) leads the way/research for compliant mechanisms. They have some of their designs open-sourced. I was able to replicate 5 of their compliant devices from the compliant mechanisms research group.

Here’s how I did it:

  • Downloaded a .stl (common 3D printing file type) editor. My favourite is Fusion 360 for its computer-aided-design (CAD) abilities.
  • Built my own version of the .stl files
  • Outsourced the files to a local 3D printing manufacturer
  • A few days later, I picked up the designs!
3D printing is a technology that turns digital files into physical objects. Perfect for nerds like me who like to ‘see’ things in action 😎

Of my five designs, 4 of them worked great, 1 of them didn’t. That’s the beauty of 3D printing, though; now that I’ve seen where the part broke (because of too little material), I can adjust the design and get it reprinted! #rapidprotyping.

However, it was exciting to ‘see’ these mechanisms IRL. The ones I built are primitive, but I can see them eventually morphing into a huge, exciting world. Let me show you :)

This is a spring design that starts 2D and becomes 3D. You can push it in either direction, and it’ll move the centrepiece up/down (like a spring).

The benefits:

  • More compact (planar means everything lies in the same plane)… it’s flat
  • Flat = simpler production
  • Simpler production = cheaper

This print was a good example of how LEMs work. One mistake I made was the material used for printing. It’s a bit too stiff. This makes the part less susceptive to a load (e.g., a hand), which means it takes more force to make the motion. This taught me something important: material selection is crucial to compliant design.

If you think about your heart, part of the reason why it’s such a suitable mechanism is its material. Sure, it might have a great topological shape + structure, but if your heart were made out of brain cells, it wouldn’t work. I’ve got to be careful that I’m not making a heart out of brain cells when 3D printing!

Origami is making its mark on medicine! The art of paper folding is another type of compliant mechanism (it gets its motion from non-rigid parts).

The design I printed was inspired by origami “chompers.” It’s a prototype of something with the ability to grab things.

This could be used within our bodies (as a nano-device), or at the tip of a surgical instrument. The design is simple, effective and easy to manufacture. And, it’s made entirely out of tough plastic!

One item can really be two items…

These are its two possible positions

This is a mechanism that has two resting positions. It has two resting states, and quickly switches between both. We can use a similar device for space release devices and electrical switching devices. These small mechanical devices allow one item to be in two different forms.

This one is probably my favourite. Whenever you apply a light force (except for the base), the elephant will move every part except the bottom of its trunk. The region gets stabilized in mid-air! This demonstrates the precision of these devices.

An application for a stabilized trunk? Imagine the ‘end’ of the trunk had nuclear reactors. If there were an earthquake, the surrounding regions would move, but the reactors would stay in place. No explosions!

The fail 😅

Instead of the force making it to the ‘plier’ part, it broke the high-stress area. I guess mistakes are all part of the prototyping process… 😜

This one didn’t work out because the middle piece didn’t fit in properly, which caused stress to a portion of the part. The lack-of-material caused it to be too weak.

What could it theoretically do? We can build cheaper, lighter tools.

I find it pretty extraordinary that we can build the tools we’re used to (e.g., pliers) in a dramatically different way. What other things are waiting to be redesigned in a bendable way?


My imagination is going wild. There are so many applications! I’m now sitting in a subway station, and I saw a young child in a wheelchair. If we didn’t invent the wheel, his ability to move would have been impossible. If it wasn’t for the piston, there would be no steam engine; without steam engines, there’d be no cheap energy for us to use. Almost everything I do relies on energy. 🤯

All of the ‘industrial’ things around us have shaped our lives. Compliant mechanisms will diversify our ability to animate the world. Who knows what will happen?


👋I’m Izzy, and I love learning about the future. This is the start of my series on compliant mechanisms. Hit the follow button to stay up-to-date with my work; and/or connect on Linkedin/Twitter.

Isabella Grandic

Written by

Hey, I’m Izzy, a 16-year-old on a trajectory towards impacting billions with emerging tech. I’m super excited about cellular agriculture and machine learning.

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