The SpectroClick Origin Story Part III : A New View of Serendipity

SpectroClick President Alex Scheeline

The day the Vietnam National University of Science – Hanoi students first worked on assembling their rudimentary spectrometers was May 21, 2009. Because of all the chatter in the classroom, I thought they understood the task and were highly involved. Not until two years later did Bùi Anh Thự inform me that, in fact, the students were highly confused, didn’t know what was happening, and didn’t feel they were learning much. But at the time, it looked like they were playing with positioning the components, aligning the spectra in their cameras, and learning a lot.

I asked the students to transfer their data to thumb drives and bring them to class the next day, when we would go over how to analyze the data. What I didn’t realize was that some students had discarded used components on the floor, leaving them as trash. And what I also didn’t know was that Thự was intrigued by the diffraction patterns and wanted to create more patterns, so that at the end of class she went to the back of the room and harvested many of the discarded batteries, LEDs, and, most importantly, diffraction gratings. She took them home, waited for sunset, and started playing with them in a darkened room.

DOUBLE DIFFRACTION GRATING
RL5-W5020 white LED, powered by a 3 V lithium battery, as observed through a double-diffraction grating. Bùi Anh Thự, May 21-22, 2009.

At the beginning of class the next day, Thự was the only student who brought in data. I looked at one of the double-dispersion pictures of the LED, which she took against a dark background. “Could I use this in discussing the data with the class?” I asked. “Yes,” replied Thự. And so it was that during the second hour of class, Thự’s double-dispersion image was projected for all to see. We reproduce it here as the DOUBLE DIFFRACTION GRATING image. As Prof. Thai videoed the proceedings, I started discussing the image, and loaded it into the data analysis software. While the screen of Thự’s data wasn’t captured while in Hanoi, a screen showing spectra for blank and absorbance of Methylene Blue appears below to give some idea of what was being projected.

METHYLENE BLUE SPECTRUM
Data analysis software used with the “cell phone spectrometer” experiment. Image originally published in the Journal of the Analytical Sciences Digital Library, entry 10059, open access (2009).

It dawned on me that I was seeing something unusual, something that might solve a problem of long-standing. As the order number increased, the throughput went down, but the dispersion increased. Thus, there was a trade-off among resolution, throughput, and dynamic range.

I did not recognize at the time that control of exposure time was a problem. In 2009, simple “point and shoot” cameras and early cell phone cameras automatically adjusted exposure to maintain a pleasing appearance, thus destroying the ability to measure the absolute intensity of light. Since that time, exposure control has come to the software systems used by widely available digital cameras. But back then, I only vaguely understood and explained the exposure problem to the class.

I then said, “If we could figure out how to get a lot of orders to look at, we could optimally trade off throughput, resolution, and dynamic range.” This trade-off had hounded users of array detectors since their invention in 1973. At which point, Bùi Anh Thự quietly said, “Show the video!” “Video? What video?” I thought, in a state of confusion because I had seen only the still image from the double dispersion grating.

Thự came to the front of the room and opened a second file from the thumb drive. The video she shot the evening before looked at light transmitted through several gratings, one adjacent to the LED, the other two just in front of her camera lens. It showed some of the most glorious multi-order spectra imaginable. She had also taken some stills, the best of which, what I consider to be the founding image of SpectroClick, is shown here:

STACKED DOUBLE DISPERSION GRATINGS
LED viewed through 3 stacked double-dispersion gratings. Taken by Bùi Anh Thự
May 21-May 22, 2009, and displayed to the K51 class, Hanoi University of Science Faculty of Chemistry, May 22, 2009.

It was hard for me to finish class after seeing the multi-order spectral pattern for the first time. Keep in mind that all I expected to see was an image like the first DOUBLE DISPERSION GRATING image above, but instead I saw the complex array with the capability of solving the long-standing instrumentation performance trade-off problem. At the end of class, I stepped off the dais, walked straight to Thự, and said, “We’ve got to protect your intellectual property rights. You just made a patentable invention.” She responded in disbelief, “I did?”

Over the following days and weeks, the Faculty of Chemistry and Hanoi University of Science indicated no financial or equity interest in the invention. We filed a disclosure with the University of Illinois. By late fall, I sent a small optical bench to Thự in Hanoi so she could work with the diffraction gratings to get an understanding of how they function, which neither of us understood at the time. While still an undergraduate, Thự came to Champaign-Urbana for ten weeks in the summer of 2010 to work on moving from an ingenious idea to a user-friendly instrument.

The initial spectrometer that I designed in the spring of 2010 failed – I hadn’t recognized that the LED makes a virtual image behind the grating, and the camera lens is central to imaging. Thự straightened this out, and Rob Brown of the School of Chemical Sciences Machine Shop machined a more plausible design (jointly designed by Bùi, Scheeline, and Brown). By mid-July of 2010, we had an arrangement that has since been the core of SpectroClick’s hardware technology.

Unlike any precedent spectrometric approach, dynamic range is not limited by detector dynamic range. Bùi Anh Thự broke a 36-year-old logjam, and is thus co-founder of SpectroClick. She returned to Urbana-Champaign in the fall of 2013 to continue instrument development. That year, we won the FACSS Innovation Award, recognizing this new technology. Bui Anh Thu now lives in Hanoi, Vietnam and is Program Coordinator at Newton School, an international high school with instruction in both Vietnamese and English.

Company founders Bui Anh Thu and Alex Scheeline, EnterpriseWorks, Champaign, IL, after winning the FACSS Innovation Award, Fall, 2013

SpectroClick, Inc. was co-founded by Scheeline and Bùi on September 11, 2011. United States Patent 8,885,161, “Energy Dispersion Device,” was granted to Alexander Scheeline and Bui Anh Thu on November 11, 2014.

Technology Tidbit 1. SATURATION and DYNAMIC RANGE DISCUSSION

As shown in DOUBLE DIFFRACTION GRATING, it is obvious that the image is saturated in the central, zero-order image of the LED. It is less obvious, but true, that several of the first-order images (the eight images of the LED, showing some “rainbow” effect around the central white dot) are saturated in part, but the red end of the spectrum is not saturated. In the analysis software, it was clear that such reduced saturation occurred, and that the second order spectra (even further out) were out of saturation.

Ever since working in Stan Crouch’s lab at Michigan State University in the 1970s, I’d been taught, and then taught my students, that one needed diode arrays with deep wells to do absorption spectrometry because of the precision required in measuring intensity and intensity ratios. But here was a way to get dynamic range from having many orders to choose from simultaneously. But what about precision? As the order number increased, the amount of signal averaging one could do also increased! So close to 100% T, one could average information from the high orders, getting good resolution and a good reference intensity, and then when a sample was in place, at high %T, the same pixels could be used to measure transmittance. If absorbance was high, the previously saturated pixels would come out of saturation, so that lower resolution could be used to allow precise measurement of the lower intensities.

Technology Tidbit 2. SPECTROBURST™ SPECTROSCOPY DISCUSSION

SpectroBurst™ spectroscopy uses the 12-fold symmetric set of orders to provide a wide range of throughput in a single exposure, so that the dynamic range of the system is the product of the dynamic range of the detector and the grating throughput. Resolution depends on optical aberrations, entrance aperture size, light collimation prior to the grating, and focusing of the camera. Whether resolution is set by the optics or by the size of observation pixels depends on the specific system. Unlike any precedent spectrometric approach, dynamic range is not limited by detector dynamic range.

The SpectroClick Origin Story Part II: Return to Hanoi

SpectroClick President Alex Scheeline

In the fall of 2008, as I was gathering parts and writing software for the rudimentary spectrometer at the University of Illinois at Urbana-Champaign (UIUC) to take to Vietnam National University of Science – Hanoi for the Chem 420 class, I started working with the EnLIST program. EnLIST sought to assist Illinois high school teachers in becoming more effective in the classroom, and they looked forward to training their first cadre the following summer. Teaching assistant Kathleen Kelley was assigned to help prepare the labs. We decided to also use the spectrometer with the EnLIST participants. My “single use” rudimentary spectrometer, originally dreamed up for one-time use in Vietnam, had additional users even before the first mock-up was completed.

We needed to figure out how to connect a battery to the LED light source. Kelley went to the Electrical Engineering storeroom to select a battery and battery holder. She returned with a lithium button battery just the right size so that friction would hold the LED in place. “Brilliant! One less part to worry about, and we don’t need to solder!” I said. The internal resistance of the battery and the exponential response curve of the LED just balanced, giving a stable light source.

By April 2009, I had prototype software running to interpret the JPGs from the rudimentary spectrometer. A key contribution was that of UIUC Chemistry Professor Emeritus Stan Smith, one of the originators of computer-assisted instruction. Because we couldn’t trust how the cameras would line up with the spectra, the students had to tell the software where the data lay. “How do I extract data situated at an angle?” fussed and thought, and then asked Smith for advice. Drawing the problem on a white board, I showed Smith the image rotation problem. Smith put up his hand at an angle and twisted it straight. “Just rotate the picture until the line you’re trying to extract starts at a known place, going in a known direction,” he said. In the blink of an eye, the problem was, in principle, solved. After a few days of programming, semi-automatic data extraction was a reality.

As I prepared to leave for Hanoi, I wasn’t sure if I could take the lithium cell batteries by air to Vietnam. After a bit of inquiry, including talking with personnel at American Airlines and the Transportation Safety Administration, it appeared that as long as the batteries were in their original packaging and in carry-on baggage, it was permitted. I took an additional step: after I received the parts, I didn’t open any of them to check that the right items had been received, I just put them in my carry-on so the original packaging was intact. Included were linear diffraction gratings, 1 cm plastic clear cuvettes, photocopies of the baseplate design on cardstock, batteries, and LEDs.

In May 2009, I went back to Vietnam to teach Chem 420, Instrumental Analysis, to the same undergraduate K51 class who took Chem 222 the year before. But this time, Vietnamese faculty had already taught much of the class content. Students were to present lectures; I gave only one lecture per day, and there were daily in-class projects, allowing the students to teach themselves. In many ways, with so much active learning, it was the best large-class teaching I ever did. Nguyen Thi Thai, one of the HUS faculty, videoed many of the lectures. It was not at all clear that I would ever return, and Thai wanted to ensure that at least some of the lectures were preserved for future classes.

And so the day came, May 21, 2009, when we took out the components for the students to assemble and play with, to see how diffraction gratings worked in the rudimentary spectrometer. They were supposed to collect spectrometer data using their cameras or cell phones. The plan for using the software was a little vague; I hoped they would download the software at home or bring the data back the next day on a thumb drive so it could be processed on my laptop.

We opened up and distributed the batteries. Out went the LEDs. Out went the other components. And then came the surprise. Edmund Scientific had sent double dispersion gratings instead of linear dispersion gratings. I was stunned – I’d never seen such gratings before. They diffracted light in both the x and y directions. But I quickly recovered. “Good thing I made that software flexible,” I thought. “We can handle light no matter what orientation it diffracts in. Good job!” The students, at least in the front portion of the room, seemed very involved, they were having so much fun actually making instruments with their own hands.

Students working with the rudimentary spectrometer – precursor to the SpectroClick Kit, May 21, 2009, VNUS-H.

Three students working with Prof. Scheeline, May 21, 2009, VNUS-H.

Pictures are stills from a video made by Prof. Nguyen Thi Thai, VNUS-H.

The SpectroClick Origin Story Part 1 : One Trip Turns into Two

SpectroClick President Alex Scheeline

In 2008, I took my first trip to Asia. For decades, I thought my first trip there might be to Japan, where I had some research associates. Instead, I went to Hanoi, Vietnam to teach Chemistry 222, Quantitative Analysis, as part of a collaboration between the Faculty of Chemistry, Vietnam National University of Science – Hanoi (VNUS-H), and the Department of Chemistry at the University of Illinois at Urbana-Champaign (UIUC), where I was Professor of Chemistry.

We compressed the entire semester class, the same course as the UIUC class with 28 lectures, into two weeks with three hours of lecture per day – intense and grueling for both professor and students. Thirty-seven eager students in the K51 class awaited – they were sophomore undergraduate students, mostly around 21 years old, because their first year at VNUS-H was intensive English in preparation for the rest of their classes, all taught in English

The classroom in Hanoi, built by the French prior to 1940, was an old style lecture hall with tiered seating. In the front row, the students appeared to have the usual expressions of expectancy, but not so obvious was an unusual level of competency. By the end of those two weeks, I found that these were some of the best students I had ever had the pleasure of teaching. Among them were at least 12 future Ph.D.s. Of course, I couldn’t yet know that.

In contrast to their classroom abilities, the students lacked exposure to laboratory instrumentation. None of them had ever had their hands on any instrument aside from an analytical balance. None had seen live, in-class demonstrations. They had laboratory experience, but it was not integrated with lectures. In the United States, in-class demonstrations are common (a practice going back at least to Michael Faraday in nineteenth century England). When I asked my Vietnamese colleagues for materials to demonstrate pH indicators in front of the class, it caused a minor revolution. But I was able to do this, and bringing a spectrophotometer from the research lab to the lecture hall was greeted with enthusiasm by the students. However, I was not allowed to move additional equipment from the faculty research lab to the classroom. They were fearful that moving the one precious potentiometer would break it, preventing the faculty from conducting research.

One of the front row students was Bùi Anh Thự, a young woman who said little, and didn’t appear to be one of the “gunners.” Had she not asked to have her picture taken with me that first May (as did other students), she would have been just part of the passing crowd.

Bùi Anh Thự and A. Scheeline, May 2008, Faculty of Chemistry, Hanoi. Picture by Dao Ha Anh.

Bùi Anh Thự and A. Scheeline, May 2008, Faculty of Chemistry, Hanoi. Picture by Dao Ha Anh.

At the end of the course, the VNUS-H Dean of the Faculty of Chemistry asked, “When are you coming back to teach Instrumental Analysis, Chemistry 420?” I squirmed. How can instrumental analysis be taught to students who have never used instruments, and who will have no instruments in class? I said I’d think about it, and as I flew out of Hanoi, I was far from convinced I would ever return.

By November, 2008, it was clear that the faculty in Hanoi really wanted Chem 420 to be taught, and I was the obvious person to do it. “How did I learn instrumentation?” I asked myself. “By building instruments.” Let’s see – what could we have these students build? A chromatograph? No, they’d need to pack columns, have detectors, and have injectors; which would be impractical. What about cyclic voltammetry or some other amperometric electrochemical technique? Too expensive; I was given no budget for supplies and I’ll have to do all this out-of-pocket.

Hmm. What about spectrophotometry?” At this point, I remembered that in the back of the Berkeley Physics Series, Volume 3 (Waves) there were some cheap optical components, including a diffraction grating in a 2” × 2” cardboard mount. I pulled the book off the shelf in my office, and sure enough, just as I had left it in the winter of 1972, there was the grating. “What could we use for a light source?” Maybe a white LED and a battery. We could fold up some paper to hold the LED at the correct height. The gratings are easy to obtain, and plastic cuvettes are 25 cents apiece. So we have everything for a crude spectrophotometer except for the detector.

What could we use for the detector? And then it hit me: many of the Vietnamese students had digital cameras. A few had cameras in their cell phones, and both of these cameras made JPG files. “If I can write software to use the JPGs to do quantitative work, that should be everything needed! The students already have the detectors!” And in a flash, the rudimentary spectrometer that would become the SpectroClick Kit was born. Almost immediately, anyone who heard of the idea blurted out the iPhone slogan, “there’s an app for that!” Little did I know that patent 7,420,663 was lurking, covering all cell phone spectrometry. But why would it matter? I thought that the 8 bit cameras in cell phones had such poor dynamic range and stability that they couldn’t be used for calibrated measurements.