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Design of Health TechnologiesDesign of Health Technologies
lecture 12lecture 12
John Canny John Canny
10/17/0510/17/05
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Advanced Sensing SystesAdvanced Sensing Systes
Biosensors:
!lucose onitoring
"ther systes
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#agneto$elastic sensors#agneto$elastic sensors
%!ries&%!ries& The agneto$elastic aterial resonates at a
characteristic fre'uency (hen e)cited *y aagnetic +eld,
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#agneto$elastic sensors#agneto$elastic sensors
The agneto$elastic ri**on is ade of acoercial sheet called #etglas,
The -olyer is a custo co$-olyer ade *y the
!ries grou-, .t is *elieved to (or *ecauseglucose *onds to sites on -olyer chains thatse-arate the fro other chains, This allo(s the-olyer to a*sor* (ater,
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#agneto$elastic sensors#agneto$elastic sensors
.ts fre'uency res-onse %in air& sho(s a shar- -ea(hich is deterined *y the density of the-olyer layer
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#agneto$elastic sensors#agneto$elastic sensors
esonant fre'uency in a li'uid is lo(er and the-ea is not as shar-,
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#agneto$elastic sensors#agneto$elastic sensors
re'uency res-onse in (ater varies (ith the glucoseconcentration in an alost -erfectly linearcurve,
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Sensor easureentSensor easureent
The electronics are si-le, A shar- s-ie is a--liedto a driving coil and a res-onse is easured in asense coil,
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Sensor easureentSensor easureent
The agnetic s-ie is short a*out 3 gauss for 14icro$seconds %earths agnetic +eld is a*out 0,5gauss and a refrigerator agnet a*out 10 gauss&,
The -icu- coil easures sensor activity for a further6 illi$seconds, The res-onse is transfored (ithan T to deterine the fre'uency -ea,
This should *e easy to do (ith a sall *attery$-o(ered device, ecause the sensors res-onse is'uite slo( %tens of inutes to res-ond& it isenough to tae readings every fe( inutes,
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iosensor statusiosensor status
There are any -roising systes on the hori8on*ut the only coercially$de-loyed *iosensorsare glucose onitors %9:;&, 3 ain ty-es<
Single Use: Dis-osa*le sensing aterial often=static> easureent, Chea- and -orta*le *utlo( sensitivity and accuracy,
Intermittent Use: "ften use hydrodynaics ?generally uch *etter -erforance fro sensinga oving @uid, .ts still a challenge to ove theseout of the la* and onto a chi-,
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iosensor statusiosensor status
Continuous (In Vivo) Sensors: ery econoical*ut very hard to cali*rate and ay suBer frounno(n aount of drift,
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iosensor designiosensor designe give a *rief introduction to icro$@uidic sensor
design,
hile these (ere originally fa*ricated in silicon using##S techni'ues the trend is to(ard glass and
-lastic as the su*strate,
oth glass and any -lastics allo( o-ticaleasureents *ut silicon is o-a'ue to visi*le light,
!lass and -lastic are also ore resistant tocontaination fro the cheicals used in theeasureent,
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iosensor designiosensor design
Surface immobilization: The +rst ste- is sensingis creating a selective surface to react to thesensed agent
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iosensor designiosensor design
Bead immobilization: A variation that uses *eadsto increase relative surface area,
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iosensor designiosensor design
Detection: Several ethods including resonantfre'uency of ##S cantilevers, ut a-eroetry%current easureent& is the ost (idely useda--roach, Ty-ical echaniss for current @o(include redo) cycles *et(een the target grou-
and variants,
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iosensor designiosensor design
Optical Detection: A 2Darray of agent/antigenreactions -roduces@uorescent traces<
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iosensor designiosensor design
agnetic Detection: The anti*odies areio*ili8ed on a surface and agnetic *eads*ind to sites (here the analyte is attached,
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!n8ye$"ined Iunosor*ent#ssay
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$euse
#ost iunosensors use *ound anti*odies and#ost iunosensors use *ound anti*odies and
io*ili8ation, eoving the *ound s-ecies can *eio*ili8ation, eoving the *ound s-ecies can *e
diEcult (ithout destroying the sensors,diEcult (ithout destroying the sensors,
#ethods and results vary *ut a recent detector for#ethods and results vary *ut a recent detector forChagas disease used glycine$HCl to (ash theChagas disease used glycine$HCl to (ash the
sensor and re-orted eEcacy for ore than 30sensor and re-orted eEcacy for ore than 30
cycles,cycles,
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iosensor designiosensor designS%stems&on&a&c'ip: are -roising *ut coing
slo(ly, iosensing still sees a long (ay frocoercial via*ility, ut there are soe-roising -rototy-es<
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Discussion FuestionsDiscussion Fuestions
1,1, .t ay *e a (hile *efore (e have highly.t ay *e a (hile *efore (e have highly
integrated sensors for any -athogens %andintegrated sensors for any -athogens %and
econoics dictates that they (ill coe for +rst$econoics dictates that they (ill coe for +rst$
(orld diseases +rst&, Can you thin of(orld diseases +rst&, Can you thin of
teleedicine/inforation tools to hel- facilitateteleedicine/inforation tools to hel- facilitatetraditionaltraditional %*ut si-le& la* ethodsG%*ut si-le& la* ethodsG
2,2, Sensors for edical diagnosis ay al(ays *e aSensors for edical diagnosis ay al(ays *e a
diEcult econoic -ro-osition, Can you thin ofdiEcult econoic -ro-osition, Can you thin ofother odels that ight (orG ,g, hoeother odels that ight (orG ,g, hoe
testingGtestingG