Monday, April 27, 2020

Is There A Contact-Tracing App In Your Future?

Excuse the similarity to last week's headline about immunity passports in your future, but with so little going on right now either in the economy or elsewhere, thinking about the future seems to be a good thing to do.  And it's likely that you will hear more in the coming weeks about contact-tracing apps for your mobile phone.

A contact-tracing app is designed to follow you around like a 24-hour detective, noticing everybody you've been within Bluetooth range of.  Bluetooth is a short-range communications system that virtually all mobile phones have, and its typical range is about six feet (two meters), which is conveniently just the same as the social-distancing space we are supposed to be keeping to avoid COVID-19 nowadays.  If anyone you've been near subsequently tests positive for COVID-19, this fact is communicated via the app to everyone who has come within proximity to that infected person in the last week or two, and they know to quarantine themselves and get tested too. 

In the computer geek's ideal world, not only would everybody have such an app, but the app would also take note of the physical location where the encounter with the infected person occurred.  That way you could let people even without mobile phones know that if they were in such-and-such place at such-and-such time, there was somebody there who could have infected them.

Countries such as South Korea which have implemented extensive contact tracing by non-automated means have found that it greatly reduced the need for blanket restrictions on movement, such as the U. S. and many other countries are enduring right now.  So worldwide, a number of countries are developing contact-tracing apps.  The BBC reports that Australia and Denmark hope to roll theirs out within two weeks, and Germany won't be far behind. 

In the U. S., the states of North and South Dakota as well as Utah have announced that they are working on similar projects.  However, the tech giants Google and Apple are reluctant to implement the GPS-coupled geographic data feature, because they fear that for example, if the Walmart in your neighborhood gets cited as a place where somebody could have picked up COVID-19, that could hurt the store's business. 

At an Oxford University ethics website, Bryce Goodman discusses the ethical implications of these proposed apps.  He sees it as a privacy-versus-health tradeoff, and would push the lever way toward health and away from privacy.  He points out that the same kind of privacy-intrusive data tracking is already being used to sell us things like skin cream, so why not use it to save lives? 

Until a vaccine against COVID-19 is available, we are either going to have to keep doing what we're doing now—hunkering down and wrecking the economy—or get a lot better at tracing contacts and quarantining only those people who need to be quarantined.  I agree with Goodman when he points out that the extremely blunt instrument of a general lockdown is much harder on some people than others—mainly those who can't work from home and are suffering from the lack of a paycheck, or any distinct prospect of one in the future.  So anything we can do safely to lift the economically costly restrictions should be considered seriously.

On the other hand, whatever humankind can conceive, an unkind human can hack, and it's very easy to picture how a widely-used, let alone compulsory, contact-tracing app could be twisted to cause embarrassment, loss of business, or worse.  Ideally, what would emerge from the system would be a big-data picture of the entire process of how the disease is spreading, geography and names included.  That information would have to exist somewhere, regardless of how often the proposers of the idea say it would be anonymized, because the whole point of the system is identifying people, and perhaps places as well.

There will be mistakes made, and perhaps intentionally false data provided to the system.  How would you feel if you had been doing everything right and suddenly your phone tells you you have COVID-19 and have to stay in total isolation for two weeks?  Or what if some hacker maliciously publishes the names of everybody who has contacted someone with COVID-19 in a whole city?  Welcome to Pariahville.

Those are some downsides I can think of without even trying hard, and I'm sure there are others.  On the upside, I have to admit it would be nice to go back to something approximating normal and get a haircut, pump gas, and (horrors!) even go to a movie without feeling either fearful, guilty, or both.  But I would have confidence to do such things only if I knew that my chances of catching the disease of the hour would be so small that it would fall down into the risk noise of being run over by a bus or hit by lightning.  Right now, that's not the case.

And here's where this topic folds into last week's topic:  the immunity-passport idea.  It might develop that the contact-tracing app becomes a de facto disease-free passport.  If you've been using it faithfully for however long, and if the great majority of people around you are also using it, and if it really works, the fact that it shows you are clean can be trusted.  But if I was running a movie theater, I'd want to see that green spot or whatever it would be on your app before I'd let you in.  And that would get us right back to where many citizens of China are today, who have to show a green color on their compulsory smartphone COVID-19 app before they're permitted to move around most places.  In that regard, China is not a place I would like to emulate right now.

I'm no prophet, and I can't tell whether contact-tracing apps will get very far (Singapore has had less than 25% participation in their voluntary rollout, which makes it almost useless), or will become the de-facto passport to ordinary life again.  Probably what will happen is somewhere in between.  But it will be interesting to see if we can use this high-tech solution to fight what is presently devastating many lives, both in terms of sickness and death, and in terms of economic loss and social isolation.

Sources:  I thank Michael Cook, editor of, for calling my attention to contact-tracing apps and providing me with these sources I referred to:  the BBC at and the Oxford Practical Ethics site at .  I also referred to an article from the Reuters website at

Monday, April 20, 2020

Are Immunity Passports In Our Future?

Here in the midst of the COVID-19 crisis, many of us are starting to wonder how it's going to end.  Just last Friday, Texas Governor Greg Abbott announced plans to lift certain restrictions related to the pandemic.  Regardless of what governments do, the big question people have is not so much what's happening to the economy in general, but this:  "When can I safely resume my normal way of life?" 

Some people never stopped working—notably many healthcare workers, first responders, and employees of essential businesses such as grocery stores.  But they have kept working while trying to protect themselves from the virus, and that doesn't always succeed.  For example, numerous meat-packing plants across the U. S. have shut down because of the spread of COVID-19 among their employees, despite the strict microbiological protocols that such packing plants have to observe. 

Wouldn't it be nice if there was a simple, cheap, fast blood test to tell if you have the SARS-CoV-2 virus that causes COVID-19? 

Lots of pharmaceutical companies around the world have rushed into production just such devices, referred to as point-of-care antibody tests.  Many of these are what the specialists call "lateral-flow assays."  You get a drop of blood from the patient and put it on an enclosed test strip.  As the serum flows along the strip it encounters some stuff that changes color if the blood sample has the specific antibodies that the virus in question provokes the body to make.  And a final strip turns color to verify that the stuff got that far, as a reliability check.  The whole thing takes only 15 minutes or so, and the tests can be mass-produced for as little as $3 each.

Already, governments and institutions around the world are using these antibody tests for finding out who has antibodies.  They are not intended to be used to diagnose COVID-19, however.  It takes your system a week or longer after infection to develop enough antibodies to show up on an antibody test.  So you can be walking around with COVID-19 and infecting other people, and still test negative on an antibody test.  The gold standard for having an active infection is still the laboratory-based polymerase-chain-reaction (PCR) test, done typically with a nose-swab sample that is sent to a high-tech lab, although there are point-of-care versions of PCR tests now available as well. 

But the test that is generating the most interest is the antibody test.  Presumably, a person with enough antibodies against COVID-19 is immune, although the truth of that assumption is actually still a research question that is currently being investigated.  As if that wasn't complicated enough, there are neutralizing antibodies, which confer long-lasting immunity, and binding antibodies, which just fight short-term infections.  Most of the point-of-care antibody tests detect only the binding antibodies, which indicate that you've been dealing with the virus recently.  Most people, but not all, go on to develop the neutralizing antibodies that confer immunity, but for how long, nobody knows yet.

Okay, so say I'm a manager desperate to get my factory back into production, and somebody comes along and offers me an antibody test.  I will be strongly tempted to require all of my workers and prospective employees to take the test, and only allow in the ones who test that they are immune.  Right now, that might not be a large percentage, but as time goes on and the hoped-for "herd immunity" develops, such a testing policy might be very tempting.  In effect, you'd have to have an immunity passport in order to go back to work.

Already, many health care institutions are planning to administer antibody tests, with the assumption that anyone who tests positive can't get COVID-19, or is at least much less likely to catch it, and so they might be the people you put on the front lines dealing with COVID-19 patients, reserving your non-immune staff to safer duties.

And let's get personal here.  What about teachers or others who deal with large numbers of people in close proximity?  When I was hired at Texas State University, I had to show that I passed a TB test.  That was to make sure I didn't have tuberculosis, which can be a chronic asymptomatic disease that can nevertheless be spread by otherwise apparently healthy people. 

With COVID-19, it's sort of the opposite problem.  Without a vaccine (and most experts think that's at least a year away), the only way you can safely start being in proximity with strangers on a routine basis is if most of the other people around you can't get COVID-19.  That's what herd immunity means, and we don't really know how far away from that we are, without widespread antibody testing of representative samples of the population, both apparently healthy and otherwise.

That's probably the best current use of antibody tests:  to monitor the average state of immunity in a geographic area with random sampling of both healthy and sick people.  That way, even if the tests aren't 100% accurate (and many of them fall short of that), you can factor the errors into statistics and still arrive at a pretty good aggregate number, and it doesn't matter if the odd result here or there is wrong.  In particular, it won't condemn to continued unemployment a person who has really had COVID-19 but the antibody test wrongly says he or she hasn't had it. 

A perverse situation might arise in which those of us, especially ones over 60, who have gone to extraordinary lengths to avoid catching the stuff, end up being sort of inverse Typhoid Marys.  Our employers might say, "Look here, I'll take back people who have had it and can't catch it, but you susceptible folks, you'd better stay away for a while longer until the herd immunity gets so high that it's unlikely you'll catch it regardless."  Maybe not every employer will think that way, but some of them will.

At this point, it looks like the antibody tests are simply not reliable enough to do such specifically targeted testing, especially if the results can mean continued unemployment or worse.  But look for problems to crop up along these lines, and where such problems show up, lawyers can't be far behind.

Sources:  I referred to an article on the website of the Journal of the American Medical Association by Jennifer Abbasi at  The meat-packer shutdown is described at

Monday, April 13, 2020

The Ethics of Anti-Squirrel Bird Feeders

Today is Easter, and in keeping with the tone of that holiday, I thought I'd look at something a little lighter for a change:  the ethics of squirrel-preventing bird feeders.

First, we identify the cast of characters.  There's the people who like to provide food for birds, in exchange for getting to watch the birds feed.  Next, there's the birds, who don't really have a downside in this deal, except when the squirrels get into the act and make less food available for the birds.  Third, there are the squirrels, who have to eat too, and are not to blame for the fact that watching them eat is a lot less interesting to people than watching birds eat.  And fourth, there are the companies and individuals who make bird feeders and exercise their ingenuity to make sure birds get the seed and squirrels don't. 

Maybe you haven't given the slightest thought in your adult life to birds or bird feeders.  But believe me, folks have been trying to come up with ways to stop squirrels from filching from bird feeders for decades, if not centuries.  A physics professor named Rhett Allain who blogs on the Wired website about physics in ordinary life came across a particularly clever technique.  It's a feeder put out by a company called Droll Yankees.  For the most part, it looks like an ordinary transparent-plastic-tube bird feeder, with openings for the birdseed at the bottom and a round wire perch below that for the birds to sit on as they eat—that is, birds who don't weigh as much as your average squirrel.  Because when a squirrel exercises his athletic prowess to climb down the rope that the feeder hangs on and puts his weight on the perch to get in position for a meal, the increased downward force on the perch flips a switch that goes to a battery-powered motor.  And all of a sudden, the squirrel finds himself on a merry-go-round like the one that goes out of control at the end of Hitchcock's "Strangers On a Train." 

For the animal-rights fans among their customer base, the Droll Yankees say their contraption "gently spins squirrels off the perch."  Allain found a clip taken by a satisfied customer of an unusually persistent squirrel, though, and you can view it here to judge whether the word "gently" is appropriate.  I don't think the squirrel suffered any permanent damage, but he probably had a bad case of vertigo for a while.

I have had my own problems with birdseed-thieving squirrels.  Years ago, while we were living in New England, I had my own idea about how to fix the problem.  We bought the same general kind of plastic-tube feeder that Droll Yankees sells, and hung outside our kitchen window.  This one had openings at a couple of levels, and little aluminum rods sticking out beneath the openings for birds to perch on.  Well, the space between the upper and lower rods was just enough for a squirrel to grab onto with his front legs on the upper one and his back legs on the lower one while he stuffed his face with illicit birdfood. 

We tried the usual passive things first.  A conical metal hat kind of thing hung onto the rope above the feeder was supposed to make the squirrel slide off, but he managed to swing inward while falling and catch onto the feeder anyway. 

Looking at those rods one day, I had a thought.  Being an electrical engineer, my thoughts naturally ran along electrical directions, and I recalled how one of Thomas Edison's first (non-patented) inventions was inspired by a roach-infested telegraph office he worked in.  Availing himself of the 150 volts or so that was used to energize long telegraph lines, he rigged up a pair of copper patches along a favorite roach pathway and awaited results.  Sure enough, once the roach completed the circuit, his career was at an end.

I had no desire for fried squirrel meat, so I dug around in the basement until I found a couple of transformers left over from the time a previous owner had installed the only innovative things Ma Bell ever did for consumers in the 1960s:  Princess telephones.  The phones had a little pilot light that ran off a low-power transformer that you plugged in the wall, and though the telephones themselves were long gone, the transformers were still there in the basement. 

The secondary voltage was only 6 volts AC or so, and by running this low-voltage power from one transformer out through a pushbutton switch by the kitchen window and over to the tree and onto the bird feeder, I was not endangering the house with high-voltage wiring.  But on top of the feeder, I placed the second transformer to step the voltage back up to 120, and ran one wire to each of the two poles.  You see the trend of my thoughts now.  The current was only a few milliamps, not enough to damage the squirrel, but enough to get his attention.

This was in the days before cellphone cameras (or cellphones, for that matter), but it brought a glow to my wicked heart to watch the squirrel clamber down along the rope, slide past the cone, and position himself for a nice repast, only to get the surprise of his life when I pushed the button.  He decided it was time to leave, and not by climbing up the rope either. 

The drawback of this system, of course, was that you had to stand at the window and guard the feeder, or else the squirrels would just come back when you weren't watching.  Squirrels don't take to training very well, and so while my system had great entertainment value, it didn't cut down much on the loss of birdseed to squirrels.

I'm out of space, so I will leave you, gentle reader, to ponder the ethical implications of favoring one member of the animal species while tormenting another one with centrifugal force or high voltage.  Here in Texas, we've switched to hummingbird feeders.  The squirrels aren't interested in them.

Sources:  Rhett Allain's article on the DrollYankee centrifugal squirrel-preventing bird feeder (only $200, I might add) can be found on the Wired website at  The video of the persistent squirrel is at
and the Droll Yankees feeder itself can be viewed at  A good description of the climactic merry-go-round scene in Strangers On a Train can be read at

Monday, April 06, 2020

Peter Tsai and the Electrostatic Filter Mask

Every now and then, and especially in distressed times such as these, it's good to spotlight an engineer who has done the right thing, and keeps doing the right thing.  Today I'm going to do that with Peter P. Tsai, who is credited with inventing the electrostatic non-woven filter used in the N95-type disposable masks that are such a hot topic nowadays. 

In 1995, Prof. Tsai was a materials scientist working at the University of Tennessee in the area of non-woven filter materials.  Air filters have been used for many decades to separate undesirable particles from air.  If the particles to filter out were large, almost any finely woven material whose openings between the threads were smaller than the particles could catch them.  But many of the most objectionable particles, such as tiny smoke particles and virus particles, are smaller than one micron, which is one millionth of a meter.  Just to give you an idea, a human hair is about 25 microns or more in diameter.  So we are talking very, very small.

It's almost mechanically impossible to weave cloth with fibers that are smaller than human hairs, so filter designers looked around and discovered that a mat or mesh of non-woven fibers was more effective than any woven fiber could be.  The tortuous pathways a particle has to take through the random labyrinth of a non-woven mat of fibers makes it more likely that the particle will get caught somewhere before it makes its way through the filter. 

But even with non-woven materials, there was a tradeoff between effectiveness and how hard it was to get air to go through the filter.  The thicker a filter is, the more likely it is to catch particles, but the harder it is to get air to go through it.  This problem can be fixed by making the area of the filter wider, and that is done in stationary systems such as air conditioners.  But you can't attach a portable mask to a foot-square air conditioning filter.  So there was a quandary and it looked like there weren't a lot of new ideas to make small filter masks more effective for very small particles like viruses.

At this point Prof. Tsai, and others preceding him, took a hint from the industrial filter technology known as electrostatic precipitation.  Electrostatic precipitators use high electric fields to charge dust particles and attract them to highly-charged wire grids, where they are trapped and disposed of.  They work well, but they are huge structures attached to factory chimneys and require high-voltage power supplies. 

Prior to Prof. Tsai's work, others had thought of the idea of making the plastic fibers in a non-woven filter electrified through a process known as hot charging.  When the fibers were still in a halfway-liquid form right after they are spun from a melt, it is easy to put an electric field on them that "freezes" into the plastic.  But the charging-while-hot process was tricky and probably expensive.

Prof. Tsai's innovation was to find a way to take a cold pre-fabricated mat of non-woven material and subject it to two electric discharges of opposite polarity, one after the other.  Under the right conditions, this process embedded quasi-permanent electric charges into the plastic fibers and made them very attractive to even sub-micron particles, like the 100-nanometer-diameter SARS-CoV-2 virus that causes COVID-19.  The charge is durable and will persist even if the masks are sterilized with steam, according to a new article that Prof. Tsai just put up on a University of Tennessee website.

After a career in which he obtained 12 patents and many commercial licensing agreements for his university, Prof. Tsai retired recently, but he came out of retirement to write the article I referred to, which tells health care workers how to reuse scarce N95 masks and what methods will and won't work to sterilize them without spoiling their electrostatic properties.  Another article about his work estimates that over a billion people have benefited from using masks that employ his invention of cold-charging nonwoven fibers.

Humility is not something that today's culture looks upon favorably.  The media that get the most attention these days are constantly highlighting people who use institutions as platforms to further their own fame and glory.  Even some engineering and science types (Elon Musk comes to mind) go this route and strive for public recognition, fame, and the perks that go along with these things.

Peter Tsai is not a limelight kind of guy.  A brief biography of him on the University of Tennessee website points out that he has had many opportunities to take more prominent positions, but he has stuck to his laboratory and continued to produce inventions right up to his retirement.  I don't know this for a fact, but it's quite possible that Prof. Tsai is an introvert—someone who is more comfortable working alone or with a small group of carefully chosen colleagues than he is speaking to a huge crowd at a conference, for example. 

As Susan Cain points out in a book of hers I've begun to read (Quiet:  The Power of Introverts in a World That Can't Stop Talking), much of American society is set up to favor the talkative, sociable extrovert and to view the introvert as weird or sad or even anti-social.  But introverts can do things that other kinds of people have trouble with—for instance, studying a dull materials-science problem for years until insights and hard work pay off with an innovative technique such as cold-charging nonwoven fibers. 

For two or three decades now, academia in general and engineering in particular has emphasized teamwork almost to the exclusion of allowing people to do work on their own.  I'm sure Prof. Tsai had help in doing what he's done with filter-mask materials, but I hope he'll allow me to use him as an example of what the non-attention-getter type of engineer can achieve.  By and large, he has let his work speak for itself, and now that is paying off in the lives saved, especially among medical workers, who would otherwise have inferior filtering and higher risk for contracting COVID-19.  If you are one of the lucky people these days with access to an N95 mask, take a moment to thank Prof. Tsai and his colleagues for coming up with the ideas that make such things possible.

Sources:  An article describing Prof. Tsai's work on cold-charged electrostatic non-woven filter material is on the University of Tennessee website at  Prof. Tsai's own article describing effective sterilization methods for the masks is at  And the U. S. patent for cold-charging non-woven materials that Prof. Tsai obtained in 1995 is No. 5401446, which can be viewed on Google or the U. S. Patent Office site.