
Catching It Early: New Ways of Detecting Coronavirus - sohkamyung
https://chembites.org/2020/05/26/catching-it-early-new-ways-of-detecting-coronavirus/
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isoprophlex
What is really nice about this is that they show response to actual human
samples, not just purified spike protein vs. control proteins/blanco buffer
controls. This gives me hope that a finalized test could have good
specificity...

 _Finally, clinical samples were tested to analyze the performance of the
biosensor._ _Human swab samples from a normal person and a COVID-19 patient
were collected separately. The normal sample was loaded onto the device before
the addition of the patient sample. Figure 3a clearly shows that patient
samples produce a different signal from the normal sample within a couple of
minutes. Even after diluting the patient sample 100000 times, clear responses
were observed._

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usrusr
If I get this right this sensor could be reused until it is saturated with
positive detection? (one or more positive patients depending on intensity of
the signal) That would be a complete game-changer compared to PCR where tests
that turn out negative are exactly as expensive as positives which
incentivizes against testing without suspicion.

~~~
karmakaze
This has a good impact on the economics of testing. If each test device paid
for can find one positive case, there's motivation to expand testing.

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OJFord
'Biosensors' are a really cool blend of fields, and manufactured for more
ordinary things like pH measurement too, but they (not SARS-CoV-2 ones
specifically obviously) seem to me to be completely unavailable to the
hobbyist/anyone that doesn't want to have a meeting to discuss a small sample
of 100k units to get started.

Is there just insufficient market for them to make them more available, or is
fabrication really expensive, or something else?

I asked about it recently, but no traction or comments:
[https://news.ycombinator.com/item?id=22996014](https://news.ycombinator.com/item?id=22996014)

~~~
usrusr
Lazy layman's guess, posted to provoke more knowledgeable answers: expensive
combined with very low durability. I just can't imagine semiconductor surface
doped with complex proteins to last very long when exposed to arbitrary
samples.

If I'd wanted to have this sensor in a near-future hard sci-fi I'd world-build
it the sensor to last a day at most to keep it convincing. Comes in a
cartridge of 16, each day the machine unseals a new sensor then you need to
pop in a new disk.

~~~
OJFord
I don't think that's the case - when I was looking into it prior to posting
the above Ask HN, I saw a video (a bit marketing-y, but interesting) for a
company that was deploying pH sensing ones in their packaged product dotted
around in the sea (harbour or fishery or something) in buoys for some reason
or other. It didn't seem like it was a consumable that would need continually
replacing, more like a 'deploy and forget' humidity or temperature sensor (as
in thermistor, I don't know if you can also get temp FETs).

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WilTimSon
Impressive that it catches the virus even in a highly diluted sample. I'm
trying to figure out if this also works faster than other tests? Can't tell
from the excerpt.

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spuz
If you look at figure 2a, it looks like they are dropping successively more
concentrated samples of SARS-CoV-2 onto the sensor and getting immediate
spikes in the response.

But it's not clear whether or not this technology could be developed into
something that can be used at home or in the field. That is the real challenge
you need to overcome in order to make a test with a quick response. Packaging
a sample, sending it to a lab, getting a technician to put the sample through
the test, recording the result and communicating it back to the patient - that
is what takes time not the actual performance of the test itself.

~~~
usrusr
> successively more concentrated samples

Good observation, I saw that but completely failed to consider the ascending
nature in my assessment in my first post. So reusability would have an upper
bound at the first positive. Could still be an incredibly valuable addition to
the using Arsenal of they manage to shape a deployable product around the
technology (ed if it turns out to be a car-sized behemoth, if the throughput
is right)

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acqq
Covered by ScienceDaily in April:

[https://www.sciencedaily.com/releases/2020/04/200420145029.h...](https://www.sciencedaily.com/releases/2020/04/200420145029.htm)

What I didn't find covered is how hard is to maintain the "sensing" state of
the sensor for more than a single measurement. If I understood correctly,
actual antibodies have to be put on the graphene. The described process for
that is far from trivial, in the paper:

"The fabricated graphene-based device was soaked in 2 mM PBASE (Thermo Fisher
Scientific, Waltham, MA) in methanol for 1 h at room temperature and then
rinsed several times with PBS and DI water. Finally, the functionalized device
was exposed to 250 μg/mL SARS-CoV-2 spike antibody for 4 h."

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m0llusk
It is important to be scientific about the context. There are already cheap,
fast, accurate tests for COVID-19 related antibodies. This test is comparable
to other antibody tests and not to the PCR tests which are fundamentally more
complex and slow while also being better at detective active infection.

Probably the current biggest competitor would be the Abbot Labs antibody test,
so this is really going to come down to cost, availability, and just how much
the speed matters. Little differences can really add up when doing population
scale testing, but waiting a few minutes might not necessarily be different
enough from nearly instant to be worth additional cost. It will be really
interesting to see if production of transistor based sensors can keep up with
chemical antibody test production.

~~~
mark-r
I didn't think they were detecting antibodies, they were using antibodies
built into the transistor to affect the transistor response.

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toshk
South-korea, Taiwan and a few other Asian democracies have shown great
organisational skills in this crisis.

The title "catching it early" suggested to me that the article would be about
macro solutions for societies to "catch it early".

For instance sewage detection:
[https://www.bloomberg.com/news/articles/2020-03-31/coronavir...](https://www.bloomberg.com/news/articles/2020-03-31/coronavirus-
in-sewage-portended-covid-19-outbreak-in-dutch-city)

~~~
Ensorceled
This appears to be a non seqitur. Why did the success of Asian countries make
you think that this would be about something else? Especially since a lot of
South Korea's success was tied to the their extensive testing efforts.

Taiwan's success attributed almost entirely to their taking a far more
aggressive approach to isolation than WHO was recommending (also notable,
Taiwan is not part of WHO due to China's efforts to keep them out).

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arcticbull
> Taiwan is not part of WHO due to China's efforts to keep them out.

Taiwan isn't part of the WHO because the WHO is part of the UN and broadly
speaking, member states of the UN -- the United States included -- don't
officially recognize Taiwan.

As an aside, the US relationship with Taiwan is entirely unofficial. The US
political stance follows the One China policy and recognizes Beijing as the
capital of a China inclusive of both what is colloquially the PRC and the ROC.

For what it's worth, it's likely due to the close (if challenging)
relationship the PRC and ROC enjoy that Taiwan was able to get a head start on
containment.

~~~
toshk
PRC's influence is shocking. I remember that some Taiwanese officials attended
a conference in Amsterdam called "we make the city" and even local
neighbourhood politicians were not allowed to officially meet them, let alone
take pictures with them.

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juskrey
Tests are useful. Why no one is bothering about humane side of tests outcome?
E.g. who compensates effectively lost airline ticket for someone positive
right before boarding? For we stop him/her for public safety but also punish
like criminal, what for?

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raziel2p
Travel insurance.

"punish like criminal" \- what are you talking about?

Also, you're talking about the humane side but focusing on losing money
because of void airplane tickets. I think hindering a pandemic is more humane
than worrying about losing a few hundred dollars.

~~~
juskrey
You were never flying, right? No travel insurance covers this. I am glad you
are talking about trillions of dollars in savings but against compensating
tickets lost which is often a big personal issue.

