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Modern medicine requires blood.
It is a crucial element to the successful
treatment of countless conditions.
Blood transfusions are by far the most common
procedure performed in most hospitals.
In fact, they so routine that even ambulance
EMT’s are now performing them in the field
for traumatic injuries.
The only problem is that, at least right now,
the blood we use for human transfusions has
to come from humans.
Synthetic blood substitutes are under development,
but for now, real, donated human blood is
all we can use.
This blood, though, has a shelf life.
Red blood cells, the most commonly transfused
blood product, have a government mandated
shelf life of 42 days in the US, 35 days in
Europe, and similar numbers in the rest of
There’s even some research suggesting that
red blood cells deteriorate in quality after
as little as 21 days so there’s a big focus
on getting them from donor to recipient as
quickly as possible.
Even 21 days probably seems like plenty of
time, but huge quantities of blood are taken
from huge numbers of individuals and there
are plenty of steps in between donation and
In developed countries like the UK, this supply
chain works quite similarly to any other.
The NHS Blood and Transplant division manages
the process for England and Wales.
About 90% of their blood comes from donations
given in their mobile blood banks that visit
schools, community centers, sports clubs,
and other locations.
Donors are first screened verbally and through
a hemoglobin test then a single unit of blood,
470 ml, is taken.
After a day of collection, product is taken
back to the nearest of thirteen processing
Over the following days, the blood is placed
on a centrifuge where it separates into red
blood cells and plasma.
There are then additional tests to determine
blood type and to assure it’s safe to transfuse
and then it’s packaged up and sent to hospitals
As a whole, NHS Blood and Transplant aims
to have between 40,000-50,000 units of blood
in their system at any given time to deal
with surges in demand.
While red blood cells will last for about
a month, platelets and some other blood products
will last for less than a week so this whole
process has to be sped up.
Of course, there are other products that require
fast transportation like fresh fish and flowers
but the differences between these two is that
if fish and flowers run out, people complain.
If blood products runs out, people die.
Stock out just is not possible in the blood
supply chain which means countries have to
have enough blood in their system to deal
with surges in demand associated with situations
like natural disasters and other mass casualty
Because of this, there is always a decent
amount of waste.
Blood will quite often expire before it’s
used but that’s just a luxury rich countries
like the UK have.
Collecting and certifying blood isn’t cheap
but still, they’re able to spend their way
into creating enough blood product so that
there are almost never stock outs.
Less developed countries, though, don’t
have that luxury.
Like the UK, the subsaharan African country
of Rwanda operates a system of universal healthcare
but, like the population, the government is
not rich so it can’t afford for much waste
in its blood distribution system.
The average resident of the UK makes about
$40,000 per year.
The average resident of Rwanda, on the other
hand, makes just $720.
Despite being a country of 12 million, Rwanda’s
economy is about the same size as the small
British city of Plymouth.
There’s an anomaly in the country’s indicators,
It sits as the seventeenth poorest country
in sub-Saharan Africa, well in the bottom
half, although, in terms of life expectancy,
it’s tied for forth best.
Rwanda has been identified as having one of
the best healthcare systems in Africa.
In fact, its 67 year life expectancy is higher
than that of some far richer African countries
like Namibia and South Africa.
The reason behind this no doubt has a lot
to do with the fact that Rwanda, uncharacteristically
for a poor African country, has a universal
healthcare system where everyone has access
to hospitals at an affordable or no cost,
but, in addition, some have attributed Rwanda’s
healthcare success to its willingness to embrace
One of the most visible of these innovations
has to do with how the country’s hospitals
get their blood.
They’ve outsourced much of the country’s
blood delivery to a company called Zipline
and Zipline delivers blood to hospitals across
Rwanda by drone.
This is one of the world’s first commercial
applications of drone delivery.
While companies like Google and Amazon are
testing drone delivery in developed countries,
Rwanda, a developing country, already has
a full-scale, nearly country-wide drone delivery
system in service right now.
How is works is this.
The drones currently service 21 hospitals
in the western half of the country.
The closest is just 2.5 miles or 4 kilometers
from Zipline’s facility in Muhanga with
the furthest being about 50 miles or 80 kilometers
Any of these hospitals can place an order
with Zipline pretty much in any way they can—email,
text, phone, WhatsApp, anything.
Within this building, the individual sitting
on the left takes orders, passes information
onto the next person in the process, and stays
in contact with the hospital throughout the
process to let them know when their delivery
The individual on the right is then in charge
of packaging up the delivery.
Zipline’s blood products are delivered to
them by road from the Rwandan health system
so they have a supply on-hand.
The product is packaged into one of these
The whole process is designed to be as simple
as possible so these boxes are single-use—they’re
assembled on-site from cardboard, bubble wrap,
and tape with the parachute made from paper.
That way nobody has to drive out to hospitals
to pick parachutes and boxes up.
From there, the box is passed through the
window and a bell is rung to let the next
person know the delivery is ready.
The delivery is brought over to a ready drone,
an app is used to scan QR codes to verify
the delivery and drone, then the delivery
is placed in the body of the drone.
The drone is then picked up and brought over
to the catapult.
Meanwhile, another operator comes over and
fixes the wings on the drone while another
places the battery pack in.
The drone is now almost ready for flight but
first the operators perform a visual inspection
for damage and use an app to check to be sure
all moving components are working.
During this whole process, someone else is
sitting in what’s known as the crow’s
nest performing another crucial step.
This individual is essentially air traffic
control for Zipline.
They’re in charge of the drones while they’re
flying so their first step is to coordinate
with Rwandan air traffic control to make sure
they have clearance to fly.
Now, Rwandan air space is not busy—in fact,
Zipline has about as many daily flights as
Kigali Airport, the main airport in the country—so
it’s rare to not gain clearance immediately
but still, this individual calls into Kigali
to be sure.
From there, they give clearance to the catapult
operator to launch and the catapult operator
makes sure nobody is standing in front of
There are quite often children on the other
side of the fence watching the goings on.
From there, they press the green button, an
electric motor spins, pulls the catapult,
and the drone reaches take-off speed in a
fraction of a second.
Once in-flight, the drone follows a pre-set
Now, the drone is autonomous, it flies itself,
but it has no decision-making authority.
It flies high enough where it doesn’t require
any obstacle avoidance ability and, if it
needs to hold for a minute to wait for air
traffic to clear it’s told by the controller
to enter a pre-set holding pattern.
There are few weather conditions that these
drones can’t fly through—they can handle
severe wind, rain, and lightning—but if
they can’t make it to their destination
they can also use one of these pre-set holding
patterns to turn around.
While the drones have improved greatly since
a few years ago, a critical fault does happen
every few hundred or so flights.
In this case, the drone has a built-in parachute
that it triggers itself to safely fall back
to the ground.
Crucially, no one has ever been injured by
a Zipline drone.
If for any reason a drone needs to stop flying
immediately, such as if Zipline were to receive
an order by air traffic control to immediately
get out of certain airspace, the controller
back at base could also manually trigger the
parachute to deploy.
From there, operators would go out and recover
the drone by road.
The drones fly at 60 miles or 100 kilometers
per hour so they reach the nearest hospitals
in mere minutes while the furthest hospitals,
about 50 miles or 80 kilometers away, require
about a 50 minute flight to reach.
As a drone reaches its delivery point, the
individual in charge of communication will
text the hospital to let them know.
The drone will approach the delivery point,
circle around to lose altitude, then fly a
few hundred feet over a pre-determined landing
spot, open its belly doors, and drop the package.
The parachute will slow its fall but impact
is also softened by the bubble wrap inside.
From there, the blood product has arrived
and hospital staff just walk outside to collect
For the nearest sites, these blood deliveries
arrive in about 15 minutes ready to be transfused
into patients critically in need.
But the process isn’t over yet.
The drone gains altitude, flies back towards
the Zipline site, then circles again to lose
Now, you’ll notice these drones have no
That would add unnecessary weight and complexity.
Once they’ve reached a precise altitude,
the drone will come in against the wind, about
15 feet or 5 meters above the ground, then
As quickly as the drone launched, it’s landed.
A tiny hook on the back of the drone catches
a wire-midair then the drone swings to a stop.
The level of precision needed to make this
landing process work is remarkable and is
a testament to how far drone technology has
The operators take the wings and batteries
off, put the drone back on its stand, and
it’s ready to go again, just like that.
Now, Rwanda is not a large country physically,
it’s far smaller than the UK, so you might
wonder why they can’t just rely on blood
delivery by road like the UK.
For one, Rwanda’s road infrastructure is
While the major roads are paved and in good
quality, the majority of the country’s roads
When it’s dry these roads work alright but
Rwanda sees two significant rainy seasons
from February to June and September to December
when there are heavy rains almost every day.
With this, these dirt roads can become impassable
for days due to floods and mud.
One solution could be to stock rural hospitals
with plenty of blood products to last through
periods when trucks can’t get to them but
that would lead to heavy wastage and safe,
processed blood isn’t cheap.
It would also prevent the usage of platelets
and plasma which only have shelf lives of
under a week.
Therefore, the drones make it so that, no
matter the conditions, any hospital in the
network can receive red blood products in
under an hour.
While most deliveries just serve to restock
these sites, about a third are for emergency
situations where a hospital is out of stock
of a particular blood product that a patient
Now, the potential applications of this type
of technology stretch far beyond its current
While the drones currently deliver just blood,
Zipline is testing delivery of about 500 other
medical products including bandages, medicines,
almost anything a hospital could need so that
if a hospital is missing something, they can
get it in at most an hour.
They’re also preparing to put a drone base
online in the eastern half of the country
to have nearly nationwide coverage.
One potential application of having two bases
within range of each other is that if one
base runs out of a product that is needed
on its side of the country, a drone could
be loaded from the other base, fly over, land,
have its battery replaced, and launched again
to fly to its final delivery point.
Rwanda is quite a well suited test-case for
this drone technology since it is fairly small
and densely populated but this feasibility
of transferring drones between bases could
also help create a network structure that
works for less dense countries.
The Ghanaian parliament recently approved
an agreement with Zipline to expand into their
Ghana is rather tall and narrow with density,
as a rule, more or less decreasing as one
While the exact service areas and details
have yet to be announced, what could work
on a conceptual level would be to have a number
of bases within range of each other.
The rarest, most expensive, or lowest demand
products, such as platelets and plasma, could
be stored at the southernmost base and, if
needed, could be sent north to the less busy
bases serving less dense and less busy areas
via drones stopping at each base and having
their batteries swapped.
Lastly, one other potential application for
these drones is for disaster relief.
The bare basics needed to start operations
can be packed into a single shipping container
and assembled in just a few days.
The system is designed for places like Rwanda
where road infrastructure is lacking and after
major natural disasters, road infrastructure
often is lacking.
It could be quite impactful to be able to
deploy a relatively low-cost, high frequency
delivery system over a disaster area using
drones like these.
While the Zipline system is not currently
set up for fast-deployment in disaster relief
situations, the company has considered working
on this for the future so they could set up
a base, plan flight-paths, and begin operations
So far, Zipline’s drones have, in their
initial deployment in Rwanda, served their
mission effectively of reliably linking rural
hospitals to modern medical product.
Having proved themselves with this first deployment,
the company is now entering a phase of rather
fast expansion both in the scope of service
in Rwanda and the number of countries served
Of course, the drone solution is just a bandage
on a wider problem of poor transportation
infrastructure in Rwanda and other developing
countries, but, at least in the long period
of time a developing country waits to be developed,
drone delivery might be an effective solution
for improving medical logistics fast.
There are loads of interesting physics that
go into how drones like those flying in Rwanda
For example, with a quadcopter, there’s
a theoretical limit to how large a battery
a drone can have since eventually, the extra
power needed to carry the extra weight of
the battery is greater than the extra power
the extra battery provides.
Brilliant’s classical mechanics course teaches
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Like all of Brilliant’s courses, this one
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