container or wrapper around it (even we do, in the
form of garments) – and now the technology to
manufacture and embed low-powered, single-use
sensors into disposable materials means you can be
your very own Internet of Things.
While you might think current IoT is pretty
varied (sensors recording the temperature in a house
for your smart home app, movement in an electric
toothbrush to make sure the kids are brushing
properly, or the wear on your brake pads so you know
when to replace them), they’re all essentially based on
electronics.
The IoDT is based on anything and everything
else as long as it meets one single criteria – it’s
produced cheaply enough to be discarded, which
makes substrates like paper, plastic or fabric its ideal
home.
BUILDING BLOCKS
WHILE IOT DEVICES RELY on a microchip,
transmitter and a battery to keep them going, the
inexpensive IoDT device can’t afford all (in some
cases any) of those elements as we know them.
Nevertheless, the building blocks will be the same:
sensors, telemetry to record and transmit readings,
and a power source.
INPUT SENSORS
Where IoT inputs are digital data, those of the IoDT
could be almost anything – changes to the ambient
light, temperature, pressure, mass, acceleration,
humidity, chemical make-up, force and more.
One of the critical advances ushering in the
disposable sensor world is microelectromechanical
systems, or MEMS. Most MEMS sensors are made
on silicon wafers, just like computer chips, but use
tiny mechanical structures that respond to some
physical stimulus like pressure, movement, light,
temperature and more. Only a few millimetres in
size, they can express readings as electrical signals
and – when attached to an equally tiny radio antenna
- send data to a nearby receiver.
Silicon electronic sensors cost between 10 and
50 US cents and are suitable for use in consumer
products worth $100 and up, such as phones and
fitness trackers.
Alissa Fitzgerald, founder of MEMS
manufacturer AM Fitzgerald, estimates that
disposable sensors will need to be made for less than
one cent if they’re used for items costing around
$10 in the medical, food, fitness, package tracking
or garment fields. That means the market rate for
silicon would need to be about a fifth of what it is
today (fat chance).
Your SmartHeart’s sensor is based on technology that already exists. A stent placed
inside the heart contains a membrane of quartz with an antenna inside, forming
a capacitor. When blood pressure squeezes down on the membrane it changes
the capacitance and therefore the resonant frequency of the circuit. An external
reader embedded in your shirt interrogates the antenna with an RF signal of known
frequency, then compares it with the altered frequency of the return signal.Sensors45-143cal96 BPM00Heart RateMicro processorRadiated currentsData transfer to device02 SMARTHEART
Welcome to the IoDT,
where temporary or
ultra-cheap sensors are
embedded or affixed to
any number of media that
aren’t computer-based.
Issue 86 COSMOS – 59TECHNOLOGY