Transistors That Grow On Trees

April 28, 2023 by Bryan Cockfield 16 Comments

Modern technology is riddled with innovations that were initially inspired by the natural world. Velcro, bullet trains, airplanes, solar panels, and many other technologies took inspiration from nature to become what they are today. While some of these examples might seem like obvious places to look, scientists are peering into more unconventional locations for this transistor design which is both inspired by and made out of wood.

The first obvious hurdle to overcome with any electronics made out of wood is that wood isn’t particularly conductive, but then again a block of silicon needs some work before it reliably conducts electricity too. First, the lignin is removed from the wood by dissolving it in acetate, leaving behind mostly the cellulose structure. Then a conductive polymer is added to create a lattice structure of sorts using the wood cellulose as the structure. Within this structure, transistors can be constructed that function mostly the same as a conventional transistor might.

It might seem counterintuitive to use wood to build electronics like transistors, but this method might offer a number of advantages including sustainability, lower cost, recyclability, and physical flexibility. Wood can be worked in a number of ways once the lignin is removed, most notably when making paper, but removing the lignin can also make the wood relatively transparent as well which has a number of other potential uses.

Thanks to [Adrian] for the tip!

Sawdust Printer Goes Against The Grain By Working With Wood Waste

June 13, 2021 by Kristina Panos 28 Comments

Wood-infused filament has been around for awhile now, and while it can be used to create some fairly impressive pieces, the finished product won’t fool the astute observer. For one thing, there’s no grain to it (not that every piece needs to show grain). For another, you can’t really throw it on a fire for emergency heating like you could with actual wood.

But a company called Desktop Metal has created a new additive manufacturing process for wood and paper waste called Forust (get it?) that gets a lot closer to the real thing. It might be an environmental savior if it catches on, though that depends on what it ends up being good for.

The company’s vision is to produce custom and luxury wood products — everything from sophisticated pencil cups to stunning furniture, and to take advantage of the nearly limitless geometry afforded by additive manufacturing. Forust uses the single-pass binder jetting method of 3D printing to lay down layers of sawdust and lignin and then squirt out some glue in between each one to hold them together.

Although Desktop Metal doesn’t mention a curing process for Forust in their press release, post-processing for solidity and longevity is the norm in binder jetting, which is usually done with ceramic or metal-based materials.

Let’s talk about those wood grains. Here’s what the press release says:

Digital grain is printed on every layer and parts can then be sanded, stained, polished, dyed, coated, and refinished in the same manner as traditionally-manufactured wood components. Software has the ability to digitally reproduce nearly any wood grain, including rosewood, ash, zebrano, ebony and mahogany, among others. Parts will also support a variety of wood stains at launch, including natural, oak, ash, and walnut.

Beauty and workability are one thing. But this will only be worthwhile if the pieces are strong. This is something that isn’t too important for pencil holders, but is paramount for furniture. Forust’s idea is to ultimately save the trees, but how are they going to get sawdust and lignin without the regular wood industry — they want to be circular and envision recycling of their goods at end-of-life into new goods

We wondered if the wood waste printer would ever become a thing. You know, there’s more than one way to print in sawdust — here’s a printer that stacks up layers of particle boards and carves them with a CNC.

Images via Forust

Need Strength? It’s Modified Wood You Want!

February 12, 2018 by Jenny List 29 Comments

Wood is surely one of the most versatile materials available. It can be found in a huge variety of colours and physical properties depending on the variety of the tree that grew it, and it has been fashioned into all conceivable devices, products, and structures over millenia. It’s not without shortcomings though, and one of the most obvious is that it can’t match the strength of some other materials. To carry large forces with a piece of wood that piece has to be made much larger than a corresponding piece of steel, something which is not a problem in a roof truss, but significantly difficult in a car body.

There have been a variety of attempts to strengthen the structure of wood in the past, and the latest has recently been published as a Nature paper. In it is described a process of first treating natural wood in a chemical bath to remove lignin and leave only the cellulose structure, followed by sustained compression at high temperature. This causes the cellulose fibres to interlock, and leaves a much denser wooden board with an equivalent strength that is described as near that of steel. They’ve posted a video which we’ve placed below the break, showing some ballistic tests on their material.

All new materials are of interest, but assuming that this one can be commercialised it makes for a particularly exciting set of possibilities. Wooden motor vehicles for example, new techniques for wooden aircraft or boats, or as an alternative in some applications where carbon fibre might currently find an application.

We’ve looked at a very similar process in the past for producing transparent wood. The good news for Hackaday readers that takes this from esoteric scientific paper to fascinating possibility though is that it can be done at home. Can any of you replicate the pressing step to take it to the next level?

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