Historically, technical innovations and advances began in a more rarified environment of academic research or military projects, then filtered down and expanded to the mass markets as their manufacturing processes advanced and costs decreased.
As one example, consider the resistor-transistor logic (RTL) NOR-gate integrated circuits used for the Apollo moon-mission navigation computer, shown in Figure 1. They cost about $100 each, and this is in 1960s dollars. We all know how IC density, functionality, and pricing trajectory have gone from that starting point.
However, in the last few decades, that traditional technology-transfer path has been reversed in many cases. Now, it’s just as likely that mass-market technologies and manufacturing prowess will be adapted and adopted by more advanced applications.
There are many examples of this “reverse” technology transfer. For example, the office and home inkjet printer began its widespread availability in the 1990s due to the efforts of vendors such as Hewlett-Packard, Epson, and Canon. Using MEMS technologies, some of these printers use resistive heating of tiny electrical elements to superheat the ink, causing the tiny ink bubble to “explode” out of the nozzle. Other designs used “snap action” driven by a piezoelectric element to force the ink droplet out and through the orifice.
Much of the nozzle-based deposition technology that underpins inkjet printing was also an impetus to applications beyond the original one of putting dots on paper. These include making DNA microarrays for genomics, creating electrical traces for printed circuit boards, and building 3D-printed structures (additive manufacturing).
Of course, advanced projects have always used available lower-tech components, such as pulleys, motors, connectors, and more — after all, why not? Now, however, driven by the incredible performance gains and cost drops for mass-market components, even the most sophisticated custom research projects can take advantage of their availability.
Component opportunities abound
Among the many such transitions I have read about, a recent one stands out: the adaptation of slightly modified smartphone camera-image sensors to create a detector capable of tracking antiproton annihilations in real time with unprecedented resolution. This device can pinpoint and measure the position of antiproton annihilations with an impressive resolution of 35 micrometers (+0.40/-0.22 micrometers), a 35-fold improvement over previous real-time methods.
To understand what’s going on here, you have to delve into the somewhat bizarre world of general relativity plus matter and antimatter.
At the European Organization for Nuclear Research (CERN) Antimatter Factory (what a great name!), scientists working in the Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEgIS) project collaboration are working to measure the free-fall of antihydrogen due to Earth’s gravity, with high precision. Led by a team from the Technical University of Munich (TUM), their approach involves producing a horizontal beam of antihydrogen and measuring its vertical displacement using a Moiré deflectometer that reveals tiny deviations in motion, with a detector that records the antihydrogen annihilation points.
The primary goal of the AEgIS experiment is to precisely measure the free fall of antihydrogen within Earth’s gravitational field. To do so, ultracold (≈50 K) antihydrogen traverses the two-grid Moiré deflectometer before annihilating onto a position-sensitive detector. That detector determines the vertical position of the annihilation vertex relative to the grids, and must do so with micrometric accuracy. The previous measurement option used wet-chemical photographic plates but lacked real-time capabilities — a major shortcoming.
The Moiré deflectometer is an interferometry technique where the object to be evaluated is placed in the path of a collimated beam, followed by a pair of transmission gratings placed at a distance from each other. This arrangement has been known since the early 20th century but needs a collimated light source such as a laser for effective implementation. The resulting fringe pattern, called a Moiré deflectogram, provides a map of ray deflections corresponding to the optical properties and position of the interposed object.
A detector is at the core of precision
This project needed a detector with incredibly high spatial resolution, and smartphone camera sensors now have pixels smaller than 1 micrometer. The team began with the Sony IMX219, a commercial complementary metal-oxide semiconductor (CMOS) optical-image sensor with 8 megapixels and a 3.67 by 2.76 millimeter sensitive area. (An alternative detector design in use, called Timepix3, has fifty times larger pixels and costs three times as much.)
The team stripped away the first layers of the sensors, which are made for the advanced integrated electronics of mobile phones. They then merged an array of these sensors into a single image detector with 384 megapixels, shown in Figure 2.
The detector features a large sensitive area approximately 5.8 cm by 5.7 cm, consisting of 48 individual CMOS sensors arranged in a compact rectangular tessellation. These sensors collect 56% of the antihydrogen atoms that pass through the deflectometer grids. Two outside rows of six sensors each for alignment and registration, for a total of 60 identical sensors.
Why bother?
Why are they even doing this experiment? It’s complicated, of course. At the core of Einstein’s theory of general relativity is the weak equivalence principle (WEP), which postulates the equality of gravitational and inertial mass and thus the universality of what we know colloquially as “free fall.” The WEP has been tested across various materials to very high precision, but testing it with antimatter presents a formidable challenge.
Theory and some indirect experience support the WEP for antimatter, but these are inconclusive proof, so the search is ongoing for direct experimental confirmation. The CERN/TUM team is trying to subject the WEP to more stringent tests to see if antimatter and its energy respond differently to gravitational fields compared to conventional matter.
This requires real-time detection of the position of matter-antimatter annihilations with micrometric accuracy. Using the arrangement shown in Figure 3, the team has already observed the annihilation of antiprotons on the surface of the CMOS sensor. This process results in the secondary charged particles leaving detectable signals in the exposed images.
I won’t attempt to delve into the details of how they created the stream of antiprotons for this project (don’t even think of trying it at home), nor try to explain the specifics of their results. Thus far, the antiparticles seem to obey the presumed relativistic weak equivalence principle and general relativity. If you want to know more, you can read the details in their paper “Real-time antiproton annihilation vertexing with submicrometer resolution” published in Science Advances (with over 60 co-authors!).
There’s some irony here, as this is in most technology forecasts. For many years, technical “experts” said that CMOS-based imaging devices would remain inferior to charge-coupled devices (CCDs) for “the foreseeable future.” But it looks like the foreseeable future didn’t extend very far ahead, as CMOS imagers have overtaken CCDs in both performance and cost in all but a few niche applications.
Regardless of your direct level of interest in or comprehension of this highly advanced project, it’s a clear demonstration of how mass-market, consumer-grade components can be repurposed for incredibly leading-edge work. Researchers can accelerate their projects by leveraging and taking advantage of these components while reducing risk and cost.
Antimatter in brief
Antimatter is matter composed of the antiparticles (positrons, antiprotons) of the corresponding particles (electrons, protons) in ordinary matter. It can be thought of as matter with reversed charge and parity, or going backward in time. Antimatter occurs in natural processes such as cosmic ray collisions and some types of radioactive decay, but only a tiny fraction of these particles have successfully been bound together in experiments to form antiatoms. Minuscule numbers of antiparticles can be generated at particle accelerators, but total artificial production has been only a few nanograms.
The possibility of antiparticles was proposed in the first decades of the 20th century, with the first positron image captured in a cloud chamber experiment in 1932. A collision between any particle and its antiparticle partner leads to their mutual annihilation, giving rise to various proportions of intense photons (gamma rays), neutrinos, and even other particle-antiparticle pairs. Matter-antimatter pairing and annihilation have been a theme of many science speculation and fiction stories, such as The Twilight Zone and Star Trek’s “The Alternative Factor” (1967) episode.
References
Apollo Guidance Computer, Wikipedia
Antimatter, CERN
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