Givare och system
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Givare
Elektrisk
Mekanisk
Kemisk
Biologisk
Magnetisk
Impedans
Sensor
Spänning
Ström
Frekvens
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1
Inför labben
Givarlab
Ingen labbhandledning
4 olika mätsituationer
Jobbar 4 och 4
En uppgift vid varje station!
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Mätproblem
Vad skall vi mäta?
Hur skall vi mäta?
Med vilken givare? Datablad
Lära känna givaren!!!!
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2
Instruktioner för projektpresentationer.
Presentationernas längd, 15 minuter.
Ni kan använda PowerPoint (eller
liknande)
En annan utsedd grupp opponerar ca
5 minuter
Innehåll: Ett mätsystem där ni
fördjupar er på en eller flera delar.
!
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Bedömningskriterier
• Att presentationen riktar sig till rätt
målgrupp, BME-studenter i årskurs 3
• Disposition av presentationen
• Tydlighet
• Samarbete mellan presentatörerna
• Hur hjälpmedel används
• Det tekniska innehållet i
presentationen
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!
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Alkoholsensor
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Alkoholsensor
Olika typer
Sensorerna kan vara baserade på:
• Metalloxid
• Bränslecell
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4
Alkoholsensor
Metalloxid
SnO2, mikromekaniskt tillverkad
Billig
Liten
Enkel
Robust
Enkel avläsning, resistans
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Alkoholsensor
Metalloxid
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Alkoholsensor
Metalloxid
Nackdelar:
• Ospecifika
• Ej stabila under lång tid
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Alkoholsensor
Bränslecell
• Dyr
• Bättre än metalloxid
• Ger en spänning ut
• Ospecifik
• Polisens vapen mot rattfyllerister
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Alkoholsensor
Bränslecell
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Mekaniska givare
• Tryckgivare
• Flödesgivare
• Accelerometer
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Givarprinciper
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Tryckgivare
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Tryckgivare
Historik
Rörelse överförs till en visare
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Vilket tryck
Absolut tryck
Gaugetryck
Diferentiellt tryck
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Vilket tryck
Absolut tryck
Tryck mätt mot vakuum
Gaugetryck
Tryck mätt mot atm
Diferentiellt tryck
Tryck mätt mot annat tryck
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Tryck - enheter
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Er tryckgivare
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Er tryckgivare
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µ-mekanisk tryckgivare
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Flödesgivare
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Flödesmätning
• Volymflöde, m3/s, µl/min
• Massflöde, kg/s
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Venturirör
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Bernouillis lag
Summan av lägesenergi och rörelseenergi konstant.
1
p + "v 2 + "gh = konstant
2
!
v=
q
A
!
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Venturirör
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Bernouillis lag
Summan av lägesenergi och rörelseenergi konstant.
1
p + "v 2 + "gh = konstant
2
q=
Cd " A2
$A '
1# & 2 )
% A1 (
!
2
"
v=
q
A
2" ( p1 # p2 )
! *
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!
Obstruktionsmätare
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Corioliskraft
Massflöde
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Corioliskraft
Massflöde
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Varmtrådsanemometer
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Gasflödesgivare
Honeywell
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Flödesmätare
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Accelerometer
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Accelerometer
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Accelerometer
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Micro accelerometer
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Micro accelerometer
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Accelerometer
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Accelerometer
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Accelerometer
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Mikrosensorer
Kemiska & Biologiska
sensorer
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Flow sensor
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Accelerometer
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Kapacitiv accelerometer
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Kapacitiv accelerometer
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Mikrosensorer
Varför mikro/nano
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Varför mikro/nano
• Små
• Snabba
• Kiselsensorer med elektronik
• Ingen matrialutmattning i kisel
• Ingen eller liten hysteres
• Polymerteknik (kemiska system)
• Laminärt flöde
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Varför mikro/nano
Kemi
•  Små prov volymer = låg analytkonsumtion
•  Korta diffusionslängder
•  Mikroteknologi = reproducerbara system
•  Batch tillverkning = billiga komponenter
•  Avancerade sensorer/Multisensor chips
•  High Sample Throughput (HST)
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Kiselsensorer för
termiska signaler
•  Termoelektriska effekter
•  Termoresistorer
•  Dioder och transistorer
•  Temp. sensorer för bla. flöde, tryck & IR,
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Termoelement
ΔV = (αa-αb)ΔT
Seebeckeffekten
i
metaller
1. Ferminivåns temperaturberoende
2. Diffusionskoefficienten för laddningsbärare
3. Termodiffusion
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Termospänning
mätt mot platina
Termostapel på kisel
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Termoresistans
Platina
Termoresistans i halvledare
(extrinsiskt kisel)
Resistiviteten vs. temp
Elektrontäthetets vs. temp
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Fotodiod
Elektron-/hålpar som bildas i
utarmningregionen för den backspännda
pn-övergången ger upphov till
fotoströmmen.
Karakteristik för pnfotodioden
Open circuit
Short circuit
Voc = kT/e ln(IL/IS+1)
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Olika typer av fotodioder
Optiska Givare
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Optiska Givare
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Kemiska Givare
•  Resistiva
•  Kapacitiva
•  Mekaniska
•  Kalorimetriska
•  Metall-oxid gassensorer
•  Fälteffekttransistorer (ISFET, CHEMFET)
•  Elektrokemiska (potentiometriska, amperometriska)
•  Akustiska vågsensorer
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Användnings områden
• 
• 
• 
• 
• 
• 
Medicinsk diagnostik
Implanterbara biosensorer
Monitorering i tillverknings/process industrin
Miljö analys/övervakning
Farmaceutisk screening
Forskning
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Elektrokemiska
Det finns även en mängd andra elektrokemiska mätmetoder t.ex.
olika former av voltametri.
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Kapacitiva
Kan användas till att mäta; specifika gaser, pH eller humiditet
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Fälteffekttransistorer
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Charles Lieber
• Single particle detection
• Ultrasensitive detection of
proteins for cancer
• Chemical and biological
warfare agents
• Large-scale addressable
arrays for screening in biology
and medicine
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Charles Lieber
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Charles Lieber
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Charles Lieber
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Charles Lieber
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Charles Lieber
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Sensorer för massa
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Sensorer för massa
Sara G Nilsson et al
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Sensorer för massa
S Ghatnekar-Nilsson et al
Table 1. The table shows the results from the mass loading
experiment, where f 0 is the resonant frequencies before the
deposition of the Au layer, and ! f is the frequency change after the
Au deposition. The thickness of the Au layer, !tAu , is calculated
using equation (4).
L
f0
!f
! f / f0
!m/m 0
!tAu
Figure 3. Frequency spectra from the as-fabricated array of two
cantilevers obtained before and after deposition of Au. The added
mass generates frequency shifts of 9.7 and 5.7 kHz for the 81 and
106 µm long cantilevers, respectively.
Sara G Nilsson et al
thin layer of Au was thermally evaporated on the back surface
of the cantilevers. As can be seen in figure 3 the added
mass generated different frequency shifts for the individual
cantilevers. The shorter cantilever has an original frequency
of 680 kHz. After the Au deposition the frequency was
reduced by 9.7 kHz. For the longer cantilever, with an original
frequency of 406 kHz, the frequency was reduced by 5.7 kHz.
Normalizing the frequency shifts to the original frequencies, ! f / f0 , yields the same value of 0.014 ± 0.0003 for the
two cantilevers, i.e. an accuracy of 0.1%. Assuming a uniform metal coverage and ρAu = 19.3 g cm−3 , we obtain values for the thicknesses of the evaporated metal layers (using
equation (4)) to be 12.6 and 12.5 nm for the two cantilevers,
respectively, see table 1.
Although we have by no means optimized the mass
response of this system, the experiment serves as a proof for
the MFSAC method displaying that the same relative change
in mass (!m/m ) added onto the cantilevers will generate
different frequency shifts depending on the original resonant
frequencies.
A major advantage with this system is that the frequency
response from all cantilevers is collected at the same time,
i.e. within the time frame of one measurement. The signal is
thus monitored having the same environment and conditions
for the entire array. By functionalizing each cantilever it
is possible to obtain a true label-free detection since each
frequency shift depends on the individual cantilever length.
Hence, even if the masses of the molecules interacting with
the differently functionalized cantilevers are similar, which is
not very unlikely, we will obtain discrete frequency shifts.
Assuming 100% affinity, we thus obtain a fully label-free
detection system. This is in contrast to earlier measurements
employing arrays of cantilevers of equal lengths not being
able to discriminate binding of similar masses, even though a
100% affinity is assumed. Although we have only tested this
novel concept with arrays of two and three cantilevers, there
is no reason to believe that there are any limitations in the
number of cantilevers in the array (other than pure practical
considerations such as the laser spot size). Furthermore, the
81 µm
680 kHz
9.7 kHz
0.0143
0.0285
12.6 nm
106 µm
406 kHz
5.7 kHz
0.0140
0.0281
12.5 nm
MFSAC method can easily be extended to use other detection
schemes, e.g. capacitive read-out [11].
The experiments in this work have been carried out
in ambient air conditions, serving as a proof for the
MFSAC method.
However, pursuing the method into
sensor applications in the biological area requires that
the measurements be performed in a liquid environment.
Previous work has investigated the dynamic behaviour of
Si cantilevers in liquid, and the corresponding frequency shift
as phospholipid vesicles were adsorbed onto the cantilever
surface [8]. The next step will be to combine the MFSAC
method with a liquid environment.
The approach of using a FIB system to machine arrays
of cantilevers was used as a means for rapid prototyping.
77 [12] (NIL) and electron beam
Both nanoimprint lithography
lithography [9] are viable lithography alternatives, where
the cantilever dimensions easily can reach the nanometre
scale. NIL also meets possible industrial needs. The next
approach would be to fabricate arrays of nanocantilevers,
thereby increasing the mass sensitivity both for each individual
cantilever and, using the MFSAC detection method, for the
array in total. This would generate another dimension to the
sensitivity of the system as a mass sensor providing true labelfree detection with an unprecedented resolution and detection
capability.
4. Conclusion
In this work, a novel concept of using different lengths in an
array of cantilevers has been investigated. The method has
been denoted MFSAC: multi-frequency signal analysis from an
array of cantilevers. The array of micromechanical oscillators
generated a spectrum of different resonant frequencies, where
each frequency correlated to the corresponding individual
cantilever. Although the mass response of the system was by
no means optimized, a thin layer of Au on the as-fabricated
array of two cantilevers generated the same ! f / f0 for the two
cantilevers, within 0.1% accuracy. A major advantage with this
system is that the frequency response from all cantilevers is
collected within the same time frame, offering the possibility
for true label-free detection. This simultaneous detection of
several frequencies in one spectrum has great benefits in mass
sensor applications since the same environment and conditions
prevail for the entire array during the measurements.
Enzymatiska sensorer
Glucose sensor
GOD
Glucose + O 2 " Gluconic acid + H 2O 2
GOD=Glucose
oxidase
5236
Acknowledgments
The authors acknowledge experimental assistance from Petra
Reinke and Jermaine Coleman at the Department of Materials
!
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Mikroenzymreaktor
1. anisotropt etsade vertikala flödeskanaler
2. Kanalväggarna är etsade poröst
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Enzymatiska sensorer
Glucose sensor
GOD
Glucose + O 2 " Gluconic acid + H 2O 2
GOD=Glucose oxidase
!
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Glucose sensor
Glucose sensor
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Glucose sensor
Mäter blodsockerhalten i
blodet med hjälp av
spektroskopi
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