nanobots' spring project
#FutureTech #IntricateComponents #MachineMadeMachines #Iridescent #GlowingElements #SciFiTheme #MacroPhotographyStyle #Miniaturization
#Img2img #AiArt #AiArtists #StableDiffusion #AiArtCommunity
this IRL: https://aieris.art/featured/nanobots-spring-project-eris-and-ai.html
Washington State University researchers have created the world's smallest, lightest, and fastest micro-robots, resembling a mini-bug and a water strider. Weighing eight and 55 milligrams, these micro-robots move at approximately six millimeters per second.
They feature tiny, less than a milligram actuators made of shape memory alloy (SMA) for movement without traditional motors. SMA technology allows efficient and energy-saving operation, requiring minimal electricity or heat.
The robots demonstrate remarkable agility and efficiency, with potential applications in artificial pollination, search and rescue, environmental monitoring, and robotic-assisted surgery. Future enhancements may include studying natural insect movements for optimization.
#MicroRobots #Robotics #TechInnovation #WSUResearch #ShapeMemoryAlloy #Miniaturization #ArtificialPollination #SurgicalRobotics #EnvironmentalMonitoring #BioinspiredTech
Review: Miniature battery-free #bioelectronics
"The extreme #miniaturization and long functional lifetime that are enabled by battery-free technologies point toward a future in which networks of tiny bioelectronics could be distributed throughout the body to accurately sense physiological states and apply therapies when and where they are needed." #EnergyHarvesting
(paywall, sorry, but you get the abstract)
https://www.science.org/doi/10.1126/science.abn4732
A connectome of the optic lobe of the extremely tiny fairy wasp, Megaphragma sp.
"A complete reconstruction of the early visual system of an adult insect", by Chua et al. 2023 (Chklovskii & Polilov) https://www.sciencedirect.com/science/article/pii/S096098222301237X
Don't miss the supplemental figures.
"Compared with the honeybee and the fruit fly, Megaphragma exhibits the following miniaturization-related adaptations: a significant reduction in the number of ommatidia, absence of several cell types, reduced size, and denucleation of neurons. Interestingly, the reduction in lens diameter is less than that expected from the optimization of the optical resolution of the eye. This suggests that light sensitivity is a more important
consideration when lens diameter approaches the wavelength of light. The absence of wide-field (or non-columnar) lamina neurons in Megaphragma could be a consequence of the smaller number of ommatidia, their larger acceptance angle, and the lower resolving power of the eye."
Volume assembled with #FijiSc and #TrakEM2, and its neurons and synapses mapped with #CATMAID. Woohoo!
#neuroscience #connectomics #VolumeEM #vEM #insects #miniaturization
Why It Matters
Imagine producing ultra-small electronic components, optical and microfluidic devices with unmatched accuracy. NIL's simplicity and scalability hold immense promise for cost-effective mass production of high-performance devices. It's not just about #miniaturization
🧵 about: #Nano #imprint #Lithography (#NIL) - Unveiling the Future of #Miniaturization!
Researchers at PSI have refined a process known as #photolithography, which can further advance #miniaturization in information technology. In many areas of information technology, the trend towards ever more compact #microchips continues unabated.
#Technology #MaterialScience #sflorg
https://www.sflorg.com/2023/06/tn06052301.html
Becky Stern, David Cranor, and a CT Scanner vs the Oura Ring
If you wonder how it's possible to fit a fitness tracker into a ring, well, you're not alone. [Becky Stern] sent one off to get CT scanned, went at it with a rotary tool, and then she made a video about it with [David Cranor]. (Video embedded below.)
While it's super cool that you can do a teardown without tearing anything down these days -- thanks to the CT scan -- most of the analysis is done on a cut-up version of the thing through a normal stereo microscope. Still, the ability to then flip over to a 3D CT scan of the thing is nice.
We absolutely concur with [Becky] and [David] that it's astounding how much was fit into very little space. Somewhere along the way, [David] muses that the electrical, mechanical, and software design teams must have all worked tightly together on this project to pull it off, and it shows. All along, there's a nice running dialog on how you know what you're looking at when tearing at a new device, and it's nice to look over their shoulders.
Then there's the bit where [Becky] shows you what a lithium-ion battery pack looks like when you cut it in half. She says it was already mostly discharged, and she didn't burst into flames. But take it easy out there! (Also, make sure you take your hot xylene out on the patio.)
X-ray machines are of course just the coolest thing when doing a teardown. We've seen them used from fixing multimeters to simply looking at servo motors.
Smaller is Sometimes Better: Why Electronic Components are So Tiny
Perhaps the second most famous law in electronics after Ohm's law is Moore's law: the number of transistors that can be made on an integrated circuit doubles every two years or so. Since the physical size of chips remains roughly the same, this implies that the individual transistors become smaller over time. We've come to expect new generations of chips with a smaller feature size to come along at a regular pace, but what exactly is the point of making things smaller? And does smaller always mean better?
Smaller Size Means Better Performance
Over the past century, electronic engineering has improved massively. In the 1920s, a state-of-the-art AM radio contained several vacuum tubes, a few enormous inductors, capacitors and resistors, several dozen meters of wire to act as an antenna, and a big bank of batteries to power the whole thing. Today, you can listen to a dozen music streaming services on a device that fits in your pocket and can do a gazillion more things. But miniaturization is not just done for ease of carrying: it is absolutely necessary to achieve the performance we've come to expect of our devices today.
A module from a 1950s IBM 700 computer. Note the enormous size of all components. Credit: autopilot, CC BY-SA 3.0
One obvious benefit of smaller components is that they allow you to pack more functionality in the same volume. This is especially important for digital circuits: more components means you can do more processing in the same amount of time. For instance, a 64-bit processor can, in theory, process eight times as much information as an 8-bit CPU running at the same clock frequency. But it also needs eight times as many components: registers, adders, buses and so on all become eight times larger. So you'd need either a chip that's eight times larger, or transistors that are eight times smaller.
The same thing holds for memory chips: make smaller transistors, and you have more storage space in the same volume. The pixels in most of today's displays are made of thin-film transistors, so here it also makes sense to scale them down and achieve a higher resolution. However, there's another, crucial reason why smaller transistors are better: their performance increases massively. But why exactly is that?
It's All About the Parasitics
A diagram illustrating the parasitic capacitances of a transistor. Credit: Michel Bakni, CC BY-SA 4.0
Whenever you make a transistor, it comes with a few additional components for free. There's resistance in series with each of the terminals. Anything that carries a current also has self-inductance. And finally, there's capacitance between any two conductors that face each other. All of these effects eat power and slow the transistor down. The parasitic capacitances are especially troublesome: they need to be charged and discharged every time the transistor switches on or off, which takes time and current from the supply.
The capacitance between two conductors is a function of their physical size: smaller dimensions mean smaller capacitances. And because smaller capacitances mean higher speed as well as lower power, smaller transistors can be run at higher clock frequencies and dissipate less heat while doing so.
Capacitance is not the only effect that changes when you scale down a transistor: lots of weird quantum-mechanical effects pop up that are not apparent for larger devices. In general however, making transistors smaller makes them faster. But there's more to electronics than just transistors. How do other components fare when you scale them down?
Not So Fast
In general, passive components like resistors, capacitors and inductors don't become much better when you make them smaller: in many ways, they become worse. Miniaturizing these components is therefore done mainly just to be able to squeeze them into a smaller volume, and thereby saving PCB space.
Resistors can be reduced in size without much penalty. The resistance of a piece of material is given by , where l is the length, A the cross-sectional area and ρ the resistivity of the material. You can simply scale down the length and cross-section and end up with a resistor that's physically smaller, but still has the same resistance. The only downside is that a physically small resistor will heat up more compared to a larger one when it dissipates the same amount of power. Therefore, small resistors can only be used in low-power circuits. The table shows how the maximum power rating of SMD resistors goes down as their dimensions are reduced.
Metric | Imperial | Power rating (W)
---|---|---
2012 | 0805 | 0.125
1608 | 0603 | 0.1
1005 | 0402 | 0.06
0603 | 0201 | 0.05
0402 | 01005 | 0.031
03015 | 009005 | 0.02
Small, smaller, smallest: tiny resistors compared to a 0.5 mm mechanical pencil lead. Credit: Rohm Semiconductor
Today, the smallest resistors you can buy are metric 03015 size (0.3 mm x 0.15 mm). With a power rating of just 20 mW, they're only used in circuits that dissipate very little power and are extremely constrained in volume. An even smaller metric 0201 package (0.2 mm x 0.1 mm) has been announced, but is not in production yet. But even when they do show up in manufacturer's catalogs, don't expect them to pop up everywhere: most pick-and-place robots are not accurate enough to handle them, so they will likely remain a niche product.
Capacitors can be scaled down as well, but this reduces their capacitance. The formula for calculating the capacitance of a parallel-place capacitor is , where A is the area of the plates, d is the distance between them, and ε is the dielectric constant (a property of the material in the middle). If you miniaturize a capacitor, which is basically a flat device, you have to reduce the area and therefore the capacitance. If you still want to pack a lot of nanofarads in a small volume, the only option is to stack several layers on top of each other. Thanks to advances in materials and manufacturing, which also enable thin films (small d ) and special dielectrics (with larger ε ), capacitors have shrunk in size significantly over the past few decades.
An idealized parallel-plate capacitor. Credit: inductiveload, public domain
The smallest capacitors available today are packaged in the ultra-small metric 0201 package: just 0.25 mm x 0.125 mm. Their capacitance is limited to a still useful 100 nF with a 6.3 V maximum operating voltage. Again, these packages are so tiny that advanced equipment is needed to process them, limiting their widespread adoption.
For inductors, the story is a bit trickier. The inductance of a straight coil is given by , where N is the number of turns, A is the cross-sectional area of the coil, l is its length and μ is a material constant (the magnetic permeability). If you scale down all dimensions by half, you halve the inductance as well. However, the resistance of the wire remains the same: this is because the wire's length and cross section are both reduced to a quarter of their original value. This means you end up with the same resistance for half the inductance, and therefore you've halved the quality (Q) factor of your coil.
Almost invisible: three 0201 (metric) capacitors. Image credit: Murata Electronics
The smallest commercially available discrete inductors are in the imperial 01005 size (0.4 mm x 0.2 mm). These go up to 56 nH, with several Ohms of resistance. Inductors in the ultra-small metric 0201 package were announced back in 2014 but apparently never brought to market.
There have been some efforts to get around the inductor's physical limitations by using a phenomenon called kinetic inductance, which can be observed in coils made of graphene. But even that gives an improvement of perhaps 50%, if it can be made in a commercially viable way. In the end, coils simply don't miniaturize very well. But this doesn't have to be a problem if your circuits work at high frequencies. If your signals are in the GHz range, then a coil of a few nH is often enough.
It's Not Just the Components
This brings us to another thing that has been minaturized over the past century, but which you might not notice right away: the wavelengths we use for communication. Early radio broadcasts used medium wave AM frequencies around 1 MHz, with a wavelength of about 300 meters. The FM band centered around 100 MHz, or three meters, became popular around the 1960s, while today we mostly use 4G communications around 1 or 2 GHz, about 20 cm. Higher frequencies mean more capacity to transmit information, and it's because of miniaturization that we have cheap, reliable and power efficient radios working at these frequencies.
Shrinking wavelengths enabled shrinking antennas, since their size is directly related to the frequency they need to transmit or receive. The fact that mobile phones today don't need long protruding antennas is thanks to the fact that they exclusively communicate at GHz frequencies, for which the antennas only need to be around one centimeter long. This is also why most phones that still contain an FM receiver require you to plug in your headphones before using it: the radio needs to use the headphone's wires as an antenna to get enough signal strength out of those meter-long waves.
As for the circuits connected to our tiny antennas, they actually become easier to make when they're smaller. This is not just because the transistors become faster, but also because transmission line effects are less of an issue. In a nutshell, when a piece of wire is longer than about one tenth of a wavelength, you need to take the phase shift along its length into account when designing your circuit. At 2.4 GHz this means that just one centimeter of wire already affects your circuit; quite a headache if you're soldering discrete components together, but not a problem if you're laying out circuits on a few square millimeters.
How Low Can You Go?
It has become a bit of a recurring theme in tech journalism to either predict the demise of Moore's law, or to show how those predictions are wrong time and again. The fact remains that the three players still competing at the cutting edge of this game -- Intel, Samsung and TSMC -- keep on squeezing ever more functionality into each square micron, and are planning several improved generations of chips into the future. Even if the strides they make at each step may not be as great as they were two decades ago, miniaturization of transistors continues nonetheless.
As for discrete components however, it seems like we've reached a natural limit: making them smaller doesn't improve their performance, and the smallest components currently available are smaller than the vast majority of use cases need. There doesn't seem to be a Moore's law for discretes, but if there were one, we would love to see how far one could push the SMD Soldering Challenge.
Header image: Jon Sullivan, public domain.
#engineering #featured #parts #antennas #capacitors #discretecomponents #inductors #miniaturization #mooreslaw #resistors #transistors
Snails, Sensors, and Smart Dust: The Michigan Micro Mote
If you want to track a snail, you need a tiny instrumentation package. How do you create an entire data acquisition system, including sensors, memory, data processing and a power supply, small enough to fit onto a snail’s shell?
Throughout history, humans have upset many ecosystems around the world by introducing invasive species. Australia's rabbits are a famous example, but perhaps less well-known are the Giant African land snails ( Lissachatina fulica ) that were introduced to South Pacific islands in the mid-20th century. Originally intended as a food source ( escargot africain , anyone?), they quickly turned out to be horrible pests, devouring local plants and agricultural crops alike.
Not to be deterred, biologists introduced another snail, hoping to kill off the African ones: the Rosy Wolfsnail ( Euglandina rosea ), native to the Southeastern United States. This predatory snail did not show great interest in the African intruders however, and instead went on to decimate the indigenous snail population, driving dozens of local species into extinction.
A Rosy Wolfsnail carrying a light sensing Micro Mote on its back. Source: Cindy S. Bick et al., 2021
One that managed to survive the onslaught is a small white snail called Partula hyalina. Confined to the edges of the tropical forests of Tahiti, biologists hypothesized that it was able to avoid the predators by hiding in sunny places which were too bright for E. rosea. The milky-white shells of P. hyalina supposedly protected them from overheating by reflecting more sunlight than the wolf snails’ orange-brown ones.
This sounds reasonable, but biologists need proof. So a team from the University of Michigan set up an experiment to measure the amount of solar radiation experienced by both snail types. They attached tiny light sensors to the wolf snails’ shells and then released them again. The sensors measured the amount of sunlight seen by the animals and logged this information during a full day. The snails were then caught again and the data retrieved, and the results proved the original hypothesis.
So much for science, but exactly how did they pull this off?
The Michigan Micro Mote (M3)
The low-power circuit research team at the University of Michigan, led by David Blaauw, developed an ultra-miniaturized computer they dubbed the Michigan Micro Mote. The term “mote” refers to a wireless sensor node that can measure some quantity and report its findings to a larger computer system. Tiny motes like this are sometimes referred to as "smart dust", a term that saw some hype in the early 2000s but thankfully hasn't yet lived up to some of the more apocalyptic visions.
A Micro Mote with a temperature sensor. Source: Cindy S. Bick et al., 2021
Not much larger than a grain of rice, the M3 has been dubbed the world’s smallest computer. Measuring about 2 mm x 2 mm x 3 mm, it consists of several bare chips stacked right on top of each other. Together they make up a complete wireless sensor node. Powered by a battery and a solar cell, they can measure something, store the results in RAM and send out the results using a wireless communication link.
The common thread linking the design of each of these elements is low power. And by low we mean really low: active power is in the microwatt or nanowatt level, while standby power is measured in picowatts. Such extremely low power consumption is needed because very little power can be generated and stored in the limited volume available.
Sensors
The top layer of the Mote is a sensor. The Micro Mote team has developed sensors for temperature and pressure as well as an image sensor. The temperature sensor is an ultra-low power one that can measure between zero and 100 °C, with an accuracy of about 1.5 °C, using only 71 nW. The pressure sensor is a MEMS device designed to measure the pressures inside the human body. Such a measurement can be useful in diagnosing glaucoma (when embedded in an eye) or tracking the efficacy of chemotherapy when inserted into a tumor.
A Micro Mote with an image sensor. Credit: Electrical & Computer Engineering at the University of Michigan, Ann Arbor
As for the image sensor, those looking for full-motion HD video will be disappointed: a monochrome sensor with 160 x 160 pixels is all that fits inside the volume and power constraints. A gradient index rod lens is fitted on top of the sensor to focus the image. The sensor can work in a low-power mode in which it performs motion detection by scanning a very low resolution image, only taking a full-resolution picture when there is significant movement.
The snail study actually used Micro Motes with a temperature sensor, and cleverly used the solar cell, described below, for both light sensing and power generation, eliminating the need for a power-hungry dedicated light sensor.
Data processing
A diagram showing the components of the imaging Micro Mote. Source: Gyouho Kim et al., 2014
The heart of the Mote’s operations is formed by pair of microprocessors. Both are ARM Cortex-M0s, but each is made in a different manufacturing process to either provide high performance or extremely low power. The higher-speed CPU is needed for such tasks as processing the data from the image sensor, while the lower-power CPU does general housekeeping tasks such as coordinating data flow between the different chips.
The interface between the CPUs and the rest of the system naturally had to be ultra-low-power as well. Standard buses like SPI and I2C were far too power-hungry; the research team therefore developed a new bus named MBus. Geared towards integrated nanosystems, it is able to work with subsystems that are in sleep mode or completely powered down.
Communications
The Mote's miniscule size means that there are no connectors available to get data in or out, so all communication has to be done wirelessly. Two interfaces are available for this: an optical path for system programming, and a radio link for outputting data.
Programming the Mote with light. Note how this Mote was packaged in a standard IC package for testing. Credit: Electrical & Computer Engineering at the University of Michigan, Ann Arbor
The optical path uses photodiodes that are strategically placed near the bond pads so they're exposed to ambient light. By flashing light onto them in a specific pattern, the CPU enters programming mode, enabling the user to write into the main code memory.
The sensor data can be read out again using low-power radio: the user hold a receiver near the Mote to read out any data stored in its memory. Transmitting in the 915 MHz ISM band, the radio has a range of about two meters, although Dr. Blaauw says the plan is to increase that to 20 meters. This larger range would also allow multiple motes to communicate with one another, which would enable complete self-contained sensor networks. The limited power budget and physical constraints on the antenna make this a real challenge however.
Power
The Mighty Mote is powered by a lithium battery, again miniaturized to fit in the chip stack. Its capacity is a miniscule 5.7 uAh (for the image sensing version) or 2 uAh (for the other two versions). This is about one-millionth the size of the average smartphone battery, but still enables the Mote to work for a day or two. However, this can be extended indefinitely thanks to the solar cell that forms the bottom layer of the stack. This cell has an area of about one square millimeter and generates around 20 nW, depending on the amount of light.
A power management unit (PMU) generates the proper supply voltages (1.2 V and 0.6 V) for the various chips from the battery's 3.8 V. Is also manages the operation of the solar cell, tracking its maximum power point to extract as much energy as possible. All chips also include generous amounts of on-chip decoupling capacitance, because the Mote is way too small to hook up even the tiniest of SMD capacitors.
In the Tahitian snail study, the control signals of the PMU were cleverly used for reading out the incident solar radiation. As the amount of light fluctuates, so does the frequency of the internal charge pump, and by logging this value the researchers obtained an accurate measurement of the solar radiation without having to add a separate light sensor.
Packaging
As mentioned above, a complete system is made from these parts by simply stacking the chips in a staircase-like fashion and wiring them up with gold bond wires, which is basically the same way ordinary multi-chip-modules (MCMs) are manufactured. The solar panel is at the bottom, with the sensors located at the top. The entire assembly is then encapsulated in epoxy, with transparent sections where needed.
The exact packaging design is dependent on the end application of the Mote. For the snail study, the chips were simply encapsulated in black epoxy with a window for the solar cell, then glued onto a bolt that could be threaded into a nut on the snail's shell. Motes that will be implanted into eyes or tumors will need a bio-compatible enclosure, while those meant to work in harsher environments may need a stronger package.
Applications
Early in its development, the Micro Mote was aimed at medical applications such as measuring pressure inside eyes or tumors. A similar design was also developed that could be injected into the body. Not much has been published on medical applications of the Mote since about 2016, but we imagine that's not for a lack of opportunities, since it should make development of things like smart pills much easier.
The Tahitian snail study is a great example of using wireless sensor nodes in conservation efforts. The research team is already working on another study involving monarch butterflies, which requires even more miniaturization to fit the devices to the monarchs' tender bodies.
The version with the image sensor has potential applications in security and surveillance. A wireless, autonomous camera the size of a grain of rice can easily be hidden almost anywhere. However, the limited range of the radio still precludes actual remote observation.
A company called Cubeworks, a spinoff of David Blaauw's research group, is commercializing the technology by making small wireless sensors for applications in logistics and pharmaceuticals, such as temperature logging of a chemical while it is being transported. This can help ensure that high-value goods like vaccines have been kept properly refrigerated throughout their entire journey from factory to clinic.
Overall, the Michigan Micro Mote is a great example of how to build electronic systems in an extremely confined space and with an even smaller power budget. While not exactly within reach of the average hobbyist, the basic ideas can be replicated in a larger volume using commercially available components. Snails might be a bit too small to work with, but I'm already thinking of all the sensors I could attach to my cat's collar. Something more than just a camera, of course.
[Heading image: a Michigan Micro Mote sitting on the edge of a coin. Credit: Martin Vloet, University of Michigan]
#hackadaycolumns #news #science #solarhacks #michiganmicromote #miniaturization #motes #snails
