The Economist - UK (2022-05-07)

The Economist May 7th 2022 TechnologyQuarterlyThequantifiedself 5

Oneringto rule themall

O

n the outside, the Oura ring looks ratherordinary,indistin-

guishable from a chunky wedding band. Buta faintgreenlight

that intermittently leaks out from the gap betweenfingerandring

suggests that it is not just jewellery.

The inside of the ring is packed with electronics.Thegreen

light comes from a pair of rectangular metallicspecksthatare

light-emitting diodes, or leds. Three dome-shapedbumpsthe

size of water drops contain red and infrared leds anda pairofpho-

todetectors. They are surrounded by seven temperaturesensors,a

wafer-thin battery and a miniature 3daccelerometerthatdetects

any kind of motion.

The leds illuminate the blood vessels insidethefinger.Asthe

heart pumps blood through the body, the vesselsexpandandcon-

tract and the light reflected changes accordingly.Thenumberof

these changes per minute is the heart rate or pulse.Itiscalculated

by an algorithm that takes the data given outbythesensorsand

makes adjustments for the noise in their signalbroughtonbymo-

tion, ambient light and numerous other externalfactors.

The green leds do their work by day;

the infrared ones, by night. Their advan-

tage is that they reach deeper blood ves-

sels, in which the pulse is more easily de-

tected. But their signal is even more sensi-

tive to disturbance, so needs more algo-

rithmic adjustment. The red led will,

eventually, be used to monitor blood-oxy-

gen levels. The software which will turn its

data into such measurements, though, will

be available only in a later update.

What a wearable device can measure

depends on its sensors and its software.

Lower level algorithms turn the noisy out-

put of photodetectors and the like into

heartbeats. Higher level programs com-

bine, say, heart rate, temperature and

movement into measures of the duration,

and quality, of sleep.

Sensors and algorithms combine to

help wearable devices measure step

counts, calories burned, oxygen levels and

more. Artificial intelligence (ai—as mach-

ine learning is popularly known) gives ex-

tra oomph to the algorithms. Technology

advancements in the past five years have

made it possible to pack wearable devices

with more sophisticated sensors and more

computing power. Oura’s third-generation

ring, released three years after the second,

has 32 times more memory with the same

battery life.

All that has enabled wearables to pro-

duce more accurate measures and a greater

number of them. In a recent review iqvia, a

research firm, found 384 wearable devices

marketed to consumers. They include

wrist-worn fitness trackers, sports watch-

es, smartwatches, smart jewellery like the

Ouraringandsensor-bearingheadsets,patches,straps,clip-ons

andevenclothes(suchassmartsocksthatmeasurethevitalsof

babies).Justoverhalfofthedevicesanalysedbyiqviamonitorac-

tivity.Therestaredevicesthatmeasurea widearrayofhealthvari-

ables,includingsleep,temperature,breathing,bloodpressure,

oxygensaturation,bloodsugarandelectricalactivityoftheheart.

Manyofthesevariablesarestartingtoappearonpopularactiv-

ity-trackingwristbands,suchasFitbitandAppleWatch.Lotsof

devicesaddedblood-oxygenmeasurementstotheirrepertoirein

responsetothepandemicbecauselowlevelsarea signofsevere

covid.RockleyPhotonics,whichprovidessensortechnologyto

bigconsumerandmedical-devicemanufacturers,claimsitsnew-

estsensorcanmeasurehydration,sugar,alcohol,lactate(reflect-

ingmuscleinflammationfromexercise)andmuchmoreinthe

blood,aswellascorebodytemperatureandbloodpressure,which

havebeenhardtocrackinwearables.Rockleyplanstoseekap-

provalofitsnewsensorsbytheFoodandDrugAdministration

(fda), America’smedicalregulator,laterthisyear.Forhealthap-

plications,ithelpstoturnmeasurementsintothesortofinsight

requiredfordiagnosis.

Inmedicine,diagnosesoftendependonbiomarkers—specific

moleculesinbloodandotherfluidslinkedtoa particularhealth

condition.Highblood-sugarconcentration,forexample,isa bio-

markerfordiabetes.Neurologicaldiseasesareusuallydiagnosed

withstandardisedassessmentsofhowpeoplebehave,andhow

welltheyperformcertaintasks.Someofthealgorithmicmeasure-

mentsmadeby wearabledevicescan bethoughtofasdigital

equivalentsofestablishedbiomarkersanddiagnostictests.Oth-

Wearable devices measure a growing array ofhealthindicators

Tracking your health

Shoe insoles or

clip-on sensor

Cadence, balance

Ring

Movement, heart rate,

temperature, sleep

Head band

Sleep, brain electrical

activity

Glucose monitor

Blood sugar

Cheststrap

Heartrate,cadence,

balance

Smartclothing

Heartrate,ECG,

respiration,posture

Earplugs

Heartrate,respiration

Wristband

Gait,heartrate,ECG,

respiration,temperature

bloodpressure,stress,sleep

→ Wearable health electronics

Source: The Economist