> I wonder if you can make an unpickable lock with MEMS
I'm not sure what you mean. MEMS are generally tiny and I'm not sure why you'd need a ~1mm safe? But MEMS relay switches, which mechanically connect/disconnect circuits, exist.
> The other thing is, can the gears be used to store potential energy?
Springs and fluid reservoirs aren't very energy or power dense; good batteries and capacitors are much more effective and reliable. MEMS flywheels have been built and are potentially competitive, but are also extremely tricky to build.
> The key here might be if you can build a micro electric generator.
This is doable and an area of active research (for, say, charging low-power devices when a human walks, definitely not grid-scale power). Magnets are hard to work with in MEMS, so other techniques (piezoelectricity, triboelectricity) are used. [1] is currently badly-written but mentions most important bits.
> I always wondered why you needed gearing mechanisms in a micro machine. Has there ever been a practical application for gears in MEMS?
IIRC, Sandia Lab's SUMMiT V process (the source of videos like [1]) was funded in part to make mechanical latches and fail-safes for nuclear weapons, but I'm not sure what's currently in use for obvious reasons. I don't think they found many other practical applications, though experimentation led to TI's DMD chips, among other things.
Occasionally, MEMS techniques are used to make (relatively large) gears for watches.
I've also seen people try to use gears for microfluidic pumps, but I don't think any are much better than current simpler solid-state approaches.
> I wonder if you can make micro machines at this level? The MEMS thing.
At this size range, though state-of-the-art MEMS (mechanical vibrating frequency filters for RF receivers in phones, accelerometers) can have sub-100nm dimensions, basic accelerometers, pressure sensors, and inkjet heads are absolutely doable.
> Not with this PDK or process, no. MEMS processes are quite specialised.
But yeah, this is the problem. Although ICs and MEMS devices are made with similar tools, MEMS usually needs processing steps that don't play nicely with the steps in an IC process (e.g., etching away huge amounts of silicon to leave gaps and topography, or using processing temperatures and materials that mess up ICs). This SkyWater process cannot do MEMS.
A more general problem is that different MEMS devices often need different incompatible process steps, so a standardized process is infeasible (though http://memscap.com/products/mumps/polymumps tries).
However, there is a tiny chance that, if we get enough detail on the process steps and leeway in the design rules, a custom layout could implement a rudimentary accelerometer or something that works after post-processing (say, a dangerous HF bath), but only with intimate knowledge of said process steps (e.g., internal material stress levels) and a lot of luck.
There are other ways to make PCBs with a 3D printer:
Instead of etching copper, some people directly print the circuitry with a solder extruder [1]. The idea's been around for a while [2] but circuit complexity is usually very limited. Here's a guide [3] (to a similar method) that uses a hobbyist 3D printer.
To improve on the article's pen-masking method, you can mount a laser instead of a pen to the 3D printer and expose a specially coated PCB [4]. Or expose UV light through an LCD [5].
One can also just mount a milling tool to the printer and cut away the copper directly [6]. A 3D printer's not designed to take the forces from milling well, so similar but specially designed machines are made [7].
The most impressive methods are geared toward industry:
A cutting-edge industry-grade electronics 3D printer looks like [8]: an inkjet-style printer with conductive and insulating (dielectric) inks.
Somewhat related, you can use a laser etching and electroplating process ("3D Moulded Interconnect Devices" "3D MID") to make PCBs on 3D printed weirdly shaped (i.e., definitely not flat) surfaces. [9] is an impressive example, and definitely check out a search engine's image results [10].
I'll second (third?) LineageOS + microG! Full ROMs combining both are available [1] (OS updates often seem to have to be installed manually, but are supported on popular phones for years). In addition to using everything from the F-Droid repository, I can run Slack/Discord/Messenger/WhatsApp/GroupMe (though notifications are hit-or-miss) and a good few other apps (Duolingo, bank mobile apps, Uber but not Lyft). Many of these apps can be installed via Yalp Store [2], which is a frontend for the Google Play store with a built-in account to provide some anonymity. It'll do until I get a Librem5 [3].
TL;DR: no Google, most things work, but not necessarily smoothly. I've used it for a few years now.
The most complex parts of phones and computers (e.g., the CPU) are integrated circuits (ICs)[0], which are (nowadays) billions of nanometer-sized transistors on top of a piece of silicon. The way these are made is arguably the most complex, high precision manufacturing process in the world, and is usually done in multi-billion-dollar "fabs" (fabrication plant) by huge companies (e.g., Intel).
Even the most basic IC fabrication, like in the article, absolutely requires maybe ~5-10 complex tools (furnace, sputterer, etc; $1000-$10k each at current eBay prices and very low quality, if you know how to rebuild/fix all of them) and a host of supporting equipment (fume hood for seriously dangerous[1] chemical work, etc). To get reasonable results, you also need to understand the device physics and then test multiple times to get the process right. I have some serious respect for Sam Zeloof of the article for getting this to work: it's at least an order of magnitude more difficult than other home manufacturing (3D printing, woodworking, welding, sewing...), even if you're already an industry expert. And his device used 6 transistors; you'd need to get the transistor manufacturing reliability up significantly to make a useful microprocessor (instead of small analog circuits), which probably starts at several thousand transistors [2].
If (GP post) you want an automated device that makes an IC for you given a digital design file, well, hm. The closest things we have today are companies that manage and run the equipment for you (fabless semiconductor companies (Qualcom, AMD...[3]) give their chip designs to, e.g., TSMC to manufacture). Academic researchers often send parts in together to reduce costs[4], in which case you could get tens of identical (reasonably simple) chips for several thousand dollars. Someone linked to [5], which looks like an attempt at a more open, hobbyist-friendly version of the same thing. I did run across [6] once, which _does_ seem to be attempting to make an easier to use, very small, automated system. I've no idea what their status is.
A desktop device as simple to use as a 3D printer is barely even on the conceptual possibility level at the moment, and then only when people start talking sci-fi self-assembly and molecular nanomanufacturing and a century of R&D.
A single IC die (a "chiplet" when stacked on others) is made of a layer of transistors and wiring up to several hundred nanometers thick on top of a much thicker (several hundred micrometer) silicon wafer substrate.
Yep, stacking these dies ("chiplets") on top of one another is one form of 3D, and is definitely useful: IIRC, AMD's recent popular Ryzen 3000 line uses chiplets, and the Raspberry Pi's RAM chip is stacked on top the CPU (in a much cruder post-IC-manufacturing assembly process). The shorter distance between dies (compared to placing them in separate plastic packages on a PCB) can lead to maybe an order of magnitude improvement (in speed/power/etc). It's hard to stack more than a few layers.
The most ambitious form of 3D design (and the one most people probably think of) is multiple thin layers of transistors on a single die ("monolithic 3D"); this would give maybe another order of magnitude improvement. Monolithic 3D memory chips are becoming popular (V-NAND, etc), with the most recent at ~100 layers. Monolithic 3D CPUs are still an unsolved problem because they need different, more difficult process steps and better heatsinks (but we're close!).
Some other open Slack alternatives I know about include:
Matrix[1]: maybe the most impressive. A chat _protocol_ with multiple server and client implementations, gateways to everything, and just out of beta.
Zulip[2] (as mentioned), Rocket.Chat[3], Mattermost[4]---Slack clones. open source, developement open to pull requests to various degrees, can pay to have hosted in cloud or get support.
Non-free or qualitatively different solutions include Discord, MS Teams, and the original IRC, I guess.
Apologies for any inaccuracies or omissions; I'm not an expert in the space.
Digital notebooks (Electronic Lab Notebooks --- ELNs) exist, but haven't caught on yet.
Many researchers often need to be able to note down arbitrary diagrams, not just text, in real time, which pretty much means low-latency tablet with stylus. This became feasible in just the last decade or so.
Many ELNs do implement published hashes for verification ("trusted timestamping").
According to the linked statement from the UC Office of Scholarly Communications [1], "No matter what happens moving forward, UC scholars will still be able to use ScienceDirect to access most articles published prior to January 1, 2019 because UC has permanent access rights to them."
Usually, CAD programs are written for just one of several domains, outside of which they don't work as well:
- Fusion360/SolidWorks/Onshape/Catia/NX are engineering CAD programs. They are designed to make geometrically (relatively) simple parts with exacting dimensions (think vector SVG vs raster PNG) that will fit in mechanical assemblies with other parts. Models (e.g., airplanes) are often simulated for strength (FEA) and fluid flow (CFD). There are no good open source versions (FreeCAD is trying).
- SketchUp/AutoCAD are for architectural and civil purposes. These create buildings, which often have even simpler geometric features but multiple floors and plumbing and electrical runs and HVAC and other layers. I don't know too much about these.
- Blender/Maya/3dsMax are for "artistic" purposes. They can sculpt very complex shapes from triangular approximations, but are can't hold exact dimensions very well (raster PNG vs vector SVG). They are used for computer graphics (movies, games). I'm not an expert in these, either.
I tend to design robots with Fusion, and it's definitely better for my purposes than SketchUp (no easy watertight meshes, assemblies, simulation), but know people who work in different domains who therefore use other programs.
- Fused deposition modeling (FDM): the typical plastic filament-extruding hobbyist printer. Low resolution, but fast and creates very strong parts in one of wide varieties of well-known engineering materials. Tricks (e.g., two extruders) can give limited multiple colors or materials.
- Selective laser sintering (SLS): a laser melts a pattern into one layer of powder at a time. Can make even stronger parts than FDM by using nylon, titanium, etc. Very common in industry, but usually too expensive for hobbyists. These are the printers used to make rocket engines.
- Stereolithography (SLA) as explained above works like SLS but cures liquid resin with light instead of melting powder. Has many subvarieties. Advantage is scary high resolution (certain engineering choices give 160 nm (!) feature size [1]), but at the cost of relatively limited material choices because materials need to be liquid UV curable (though Form 2 has a good library now [2]) and definitely no multi-material or color parts. I'd consider this new 3D rotation printer a variety of SLA. [Edit: for clarity, I lumped CLIP and DLP here with SLA]
- Inkjet-based printers: these are the _really_ cool ones. Objet makes a printer [3][4] that uses inkjet heads to deposit multiple colors and materials in the same part layer-by-layer (kind of combining FDM and SLA). Upside is multiple colors and materials and resolution (e.g., Lego uses these for prototyping), downside is ridiculous price and low speed. Other printers like HP's and Z Corp's combine inkjet heads with SLS powder instead.
There are also a few weirder ones, e.g., paper layering, but I don't think they're widely used.
This post is very well written! I like the colloquialism, exhaustive list of experiments (both successes and failures, to better educate others), future work and call to action, and a pervasive lack of fluff. In particular, this reads like many contemporary scientific papers, but is much clearer (I can understand everything with one pass - whoa!), albeit absent tabled data and extreme technical details. I wish more scientists wrote like this.
IIRC, Syncthing is decentralized P2P and synchronizes standard tree(ish) filesystems (like most similar projects). Perkeep does away with the filesystem and instead uses a blob-based merkle-tree-like system with good properties for very long term archival (and as a side effect, can also use P2P and multiple encrypted cloud backups easily). So Syncthing can copy preexisting file structures and fits in usual workflows, but Perkeep has some data storage benefits. I don't know how their performance compares.
A (non-exhaustive) list of hobbyist-accessible engineering CAD programs I can recommend:
- Fusion 360 (Windows/Mac) (free for hobbyists) can do complex many-component robots or simple geometric shapes and has facilities for rendering and simulation. I'll concur with all the other recommendations I see here.
- OpenSCAD (Windows/Mac/Linux) (GPL) is text-based, which is nifty but really limiting. Good for generating triangulated files of complex-but-formulaic objects (e.g., gears/screws), but is ~10x slower to use than Fusion for most anything else. Would definitely not attempt to use to design an assembly of multiple parts.
- SolidWorks (Windows) ($$) is industry-standard. IMO, slightly better (smoother/faster/more robust) for modelling medium-to-large things than Fusion 360.
- OnShape (clound-based) ($$ but IIRC has hard-to-find public/free tier) is notable for working in a web browser (good for Linux users). Seems to have a bunch of plugins, but actual CAD capability is run-of-the-mill. [EDIT: also has a functional CAD-on-phone app. Like, wow.]
- FreeCAD (Windows/Mac/Linux) (GPL) is the open source Fusion/SolidWorks equivalent option. Needs a lot of work (e.g., good part assembly capabilities) and I find it rather clunky. I wouldn't learn CAD here, but I do really want a community-developed Linux desktop CAD program.
Good for WiFi/IMU-based indoor (phone-based) position tracking, I believe. For more accuracy, especially for robotics, etc., Pozyx [1] claims resolution of "a few centimeters" (indoor rooms/outdoor) by using some custom trilateration circuitry, and then there are attempts to use VR (esp. Vive) methods [2], which are even better (albeit more limited range).
I'm not sure what you mean. MEMS are generally tiny and I'm not sure why you'd need a ~1mm safe? But MEMS relay switches, which mechanically connect/disconnect circuits, exist.
> The other thing is, can the gears be used to store potential energy?
Springs and fluid reservoirs aren't very energy or power dense; good batteries and capacitors are much more effective and reliable. MEMS flywheels have been built and are potentially competitive, but are also extremely tricky to build.
> The key here might be if you can build a micro electric generator.
This is doable and an area of active research (for, say, charging low-power devices when a human walks, definitely not grid-scale power). Magnets are hard to work with in MEMS, so other techniques (piezoelectricity, triboelectricity) are used. [1] is currently badly-written but mentions most important bits.
[1] https://en.wikipedia.org/wiki/Nanogenerator