1. Fingerprint sensing techniques
Biometrics Tech. and Application
Dr. Hsu, Wen-Hsing

2. Fingerprint sensing techniques
Optical readers
Reflection
Transmission
Sweep, sweep with a roller
Touchless
TFT
Electro-optical readers
Capacitance
Silicon chips
RF field - AC capacitance
Pressure
Resistive membrane on silicon, TFT
Tactile MEMS
Thermal
Ultra-sound

3. Ink
Ink and paper are the tried-and-true way to take fingerprints, but technology has found ways to eliminate smudges and ink stains.

4. Optical readers Reflection
The oldest 'live-scan' readers use frustrated refraction over a glass prism (when the skin touches the glass, the light is not reflected but absorbed). The finger is illuminated from one side with a LED while the other side transmits the image through a lens to a camera. (FTIR: frustrated total internal reflection).

5. Optical readers -Reflection
Many companies are offering such devices, this is a common technology. .
Here is the example of the Compaq fingerprint reader (CMOS camera, around 2000).
Generally, one fingerprint is taken at a time, but some devices are able to acquire several fingers at a time. (Rolling Fingerprint)
Nagoya University uses a micro-collimator instead of the fiber optic, enabling direct fingerprint comparison.

6. Reflection with sweep
Kinetic Sciences and Cecrop/Sannaedle have proposed sweep optical sensors based on this principle. Cecrop seems to have abandonned this device
Kinetic Sciences Paper describing the sensor
Cecrop/Sannaedle

7. Casio + Alps Electric uses a roller with the sensor inside
Casio + Alps Electric uses a roller with the sensor inside. The roller acts like the prism.
Casio
Alps Electric
As well as Digital Persona with the Firefly
Digital Persona Firefly

8. Reflection touchless
TST removed the prism by directly reading the fingerprint, so the finger does not touch anything (but still need a guide to get the right optical distance). Thales (formerly Thomson-CSF) also proposed the same, but with the use of a special powder to put on the finger. The BERC lab from Yonsei University (Korea) also developped a touchless sensor (2004). (2005) TBS launch a touchless sensor with the "Surround Imaging".

10. Transmission
It is also possible to directly read the light transmitted by the finger.

11. Mitsubishi proposes to read the fingerprint with a regular camera.

12. NEC and Delsy (and Secom
NEC and Delsy (and Secom?) use a CMOS camera which is the size of the finger, with a fiber optic in-between, the light is coming from the edges in this case. Mitsumi & NEC proposes the same but with a sweep sensor.
Delsy
NEC
Mitsumi
In July 2005, NanoIdent unveils a flexible fingerprint sensor using polymer/organic photodetector.

13. TFT optical / TFT optique
Philips replaces the CMOS sensor by a TFT display, used as sensor. Philips has also worked with Ethentica to combine their technologies, but without known product. LG has also studied a TFT sensor.

14. Other companies proposing TFT fingerprint sensors:
Casio
SiliconImageWorks
Silicon Display Technology
Alps Electric
Mitsubishi
Seiko/Epson

15. Electro-optical readers
A variant of TFT devices is the use of capacitance information instead of reflected light.

16. Some polymers are able to emit light when properly excited with the proper voltage (generally quite a high voltage is required. This polymer is directly contacting a CMOS camera, which is necessarily the size of the finger. Generally, the finger acts as the ground, and the polymer emits light where the ridges touch. Ethentica and TesTech propose such a solution.
Ethentica
TesTech

17. Capacitance
After optical sensing, the measurement of the capacitance between the skin and the pixel is the most physical effect used to acquire fingerprints. Where there is a ridge or a valley, the distance varies, as does the capacitance. Because an electrical field is measured and the distance between the skin and the pixel must be very low to provide enough sensitivity, the coating must be as thin as possible (a few microns). A significant drawback is vulnerability to strong external electrical fields, the most dangerous being ESD (Electro-Static Discharge).

18. Silicon chips + capacitance
Silicon chips can be seen as a variant of the CMOS cameras: instead of using the light, another physical effect is used.
Companies proposing (or having proposed) capacitance sensing:
Veridicom, Fujitsu, Infineon, Sony, Upek, LighTuning, Melfas, Atrua, NTT, Symwave, ...

19. Labs working (or having worked) on silicon capacitance sensors:
Seoul University
A 600-dpi Capacitive Fingerprint Sensor Chip and Image-Synthesis Technique (Lee & als, Seoul National University, 1998)
Kaist
IML KAIST
NTT
NTT Microsystem Integration Laboratories
A Single-Chip Fingerprint Sensor and Identifier (Shigematsu & als)

20. Capacitance + TFT
Flat panel technology rather than bulk silicon has been studied by Philips Korea and some others, using capacitive sensing. This is still at the laboratory stage.
A Capacitive Fingerprint Sensor with Low-Temperature Poly-Si TFTs Mitsubishi Electric Corp.
(April 2004) Alps Electric develops 2 fingerprint sensors. One is transparent, electrostatic (capacitive).

21. RF field - AC capacitance
Sometimes confused with capacitance sensing, the only common point between RF field sensing and capacitance sensing is the "capacitance" connection of the signal.
Companies proposing (or having proposed) RF/AC-capacitance sensing:
Authentec, Fingerprint Cards

22. Labs working (or having worked) on RF capacitance sensing:
Validity / Philips Korea
An alternate solution consists in having connection through wires, so the finger is not mandatory directly in contact with the silicon part.
Validity

23. Pressure
This is one of the oldest ideas, because when you put your finger on something, you apply a pressure. Piezo-electric material has existed for years, but unfortunately, the sensitivity is very low. Moreover, when you add a protective coating, the resulting image is blurred because the relief of the fingerprint is smoothed. These problems have been solved, and now some devices using pressure sensing are available.
Several solutions, depending on the material, have been proposed:
Conductive membrane on a CMOS silicon chip.
Conductive membrane on TFT.
Micro-electromechanical switches on silicon chip.

24. Conductive membrane on silicon
Opsis (a french company) offered a device using a conductive membrane deposited on a CMOS chip (July 1994).

25. Conductive membrane on TFT
Since 2002, BMF is offering a product using a TFT substrate (developed with Sanyo)
Fidelica offers since mid-2004 the FIS-3002, also using a TFT substrate from Sanyo.
(April 2004) Alps Electric develops 2 fingerprint sensors. One is based on pressure.
The Fraunhofer IKTS is working on 1-3 piezocomposites to create a fingerprint sensor (for CrossMatch, 2004).

26. Tactile MEMS
Micro electro-mechanical devices allow engineers to make extremely tiny silicon switches. When a ridge touches a switch, it closes. But the coating remains a significant problem, and moreover, a binary image is the result, leading to minimal information. No further development has been done with this technique beyond the laboratory.

27. NTT Microsystem Integration Laboratories
NTT research group
Michigan University (Wise)

28. Tima homepage
N.Galy thesis page and the thesis
Leti, pressure sensors (Rey)

29. LighTuning
Micron Technology: Tactile sensor using an insulated flexible matrix loaded with filler particles US 6,561,044

30. Thermal
Pyro-electric material is able to convert changes in temperature into a specific voltage. This effect is quite large, and is used in infrared cameras. This type of sensor doesn't measure the difference of temperature between the skin in the ridges and valleys, because the difference is negligible. In fact, as the finger is directly placed on the material, the ridge's temperature is what's measured, as it's in contact. The valleys don't make contact, so the temperature of the pyro-electric material under the valleys remains almost unchanged. A drawback of the technique is that the image disappears quickly. When you place your finger on the sensor, there is a big change of temperature, and therefore signal, but after a short period (less than a tenth of a second), the image vanishes. The finger and the chip have reached thermal equilibrium, and as there is no change in temperature, there is no signal. This effect disappears when you sweep your finger over the sensor, because of the touch/no touch of ridge/valley.
Atmel (formerly Thomson-CSF) proposes the FingerChip
Hunno Technologies & Hyung-Kew Lee (Korea, KAIST) have studied a thermal fingerprint sensor in 1999, probably using bolometers.
Nagoya University has studied a thermal sensor based on MEMS, using a resistor to heat a sensor above a cavity.
INO (Institut National d'Optique / Canada) has used bolometers to make a 160x120 pixel fingerprint sensor (US patent 6,633,656). Bolometric FPA for fingerprint recording

31. Ultra-sound
Ultra-sound fingerprint reading is not common. It may be seen as a kind of echography. Ultra-sound sensing requires quite a big device with mechanical parts, and is quite expensive. Moreover, it takes a few seconds to grab an image. It is not suited for large production volumes at low cost. Its main advantage is the reading of the derma, the sub-surface of the skin, rather than the surface.
Ultrascan
Optel is still at R & D stage
Surface impedance impediography
(2004) CrossMatch is developping a fingerprint sensor based on piezo-electric pillars glued in teflon and covered with urethan, based on ultra-sound

32. Fingerprint: List of silicon sensors

33. List of fingerprint sensors / sensing area / JF Mainguet 2005 ( sweep sensor area sensor)
Company
Sensing type
Brand T
Part number
Release date
Res. dpi
x pixel
y pixel
x mm
y mm
notes
Atmel formerly Thomson-CSF
thermal
FingerChip
FC8x8
1997
508
160
8.0
prototype
FC2x17
350 40
17.5
2.0
FC15A140
1998
280 30
14.0
1.5
AT77C101B
2000 8
0.4
formerly FCD4B14
AT77C104
2004
232
11.6
navigation
AT77C105
2005
navigation & low voltage I/Os

34. Alps
pressure -
proto
2004
optical TFT
Alps/Casio
optical roller
2003 Feb
600
288
12.2
sweep rolling tube
Atrua
capacitive
ATW100
2002
363
192 8
13.5
0.6
Formely I-Control / ICS-3000

35. Authentec spin-off from Harris
RF modulation
FingerLoc
AF-S2
2000 May
250
128
13.0 -
AFS8500
2002 May 96
9.75
Discontinued.
AFS8600
2004 Jan
Entr壆ad
AES4000
2000 Sep
AES3500
2001 Oct
500
6.5
USB. Discontinued.
AES3400
2002 Sep
AES2500
2002 Nov
192 16
0.81
USB. Replaced by the AES2501.
AES2501
2003 Dec
USB
AES2502
SSI
AES2510
2004 Jun
serial, 8 bit-parallel
1510
2005 Mar 8
6.4
0.4
4bit-parallel, master SSI

36. BMF
pressure TFT -
BLP-100
2002 Feb
438
256
384
14.8
22.2
pixel pitch is 0.058mm (width/height not OK)
BLP-60
2003
508
192
9.6
Hitachi
Casio
optical TFT
proto
2004 Oct
423
368
22.08
demonstrated over a LCD display / CEATEC 2004
2004
500
200
240
10.0
12.0
Backlight
Delsy
optical trans.
CMOS
2001
288 12 18
Discontinued?
CCD
512
576
Digital Persona
optical roller
FireFly
Firefly
2003 May
600
345
14.5
600dpi max (500dpi sweep dir.) depends on speed.
Ethentica
electro-optical
TactileSense
T-FPM
403
225
306
14.2
19.3
Formerly Who?Vision
Fidelica
pressure
FIS-3002
2004 Feb
12.8

37. Fingerprint Cards
active capacitive -
FPC1010
2002
363
152
200
10.6
14.0
FPC1011
FPC1030 32
2.2
FPC1031
Fujitsu
capacitive
MBF110
2001
500
300
15.0
(= Veridicom FPS110)
MBF200
256
12.8
USB. (= Veridicom FPS200)
MBF300
2002 Mar
1.7
Discontinued.
MBF310
2003 Jul
218 8
10.9
0.4
Replaces the MBF300.
Idex
AC capacitive
SmartFinger
2000
Sweep 1 line. Non-active pixels on silicon.
Infineon
FingerTip
FTF 1100
513
224
288
11.1
14.3
Discontinued in 2004.
INO
thermal
FPA
2003 Sep
488
160
120
8.3
6.2
Bolometers
KAIST univ.
proto
210
100
10.5
5.0
2005
462
11.0
8.8
integrated processor for recognition.
KSI / Cecrop
optical sweep
900 3
19.1

38. Leti
MEMS pressure -
proto
2002
391 92
6.0
LighTuning
capacitive
LTT C300
2003
313
192
128
15.4
10.3
LTT C500
500
236
11.8
9.6
LTT S500
2004 Oct
200 16 10
0.8
sweep-type
LG-Philips
optical TFT
FingerTalk
2000
300
240
256
20.1
26.8
backlight
Melfas
MFCS1000
400
150
Michigan univ.
tactile
Mitsubishi
Optical TFT
2003 feb
423
250
320
15.0
19.2
capacitive TFT
2003 Feb
optical trans.
R&D
Mitsumi
optical
SEF-A1
2005 jun
600
10.8
Proto shown May 2004.
NanoIdent
photo-organic
2005
(announced resolution is likely an error)
NEC
FingerThrough
SA301-10
2002 Oct
800
480
540 15 18
(approximative values)

39. Fingerprint sweep sensing

40. Fingerprint sweep (or swipe) sensors is a subcategory of fingerprint sensors, useful because of its lower cost production compared to static (or area) sensors.
History of fingerprint sweep sensors
1997
May: Thomson-CSF (now Atmel) demonstrated the FingerChip FC2x17, at the CTST'97.
1998
May: Thomson-CSF demonstrated the FingerChip FC15A140.
May: Seoul University submits a paper about a capacitance swipe sensor (published April '99).
July: First prototype from Idex on its first sweep sensor.
1999
May: Sannaedle / Cecrop demonstrates MyFin, a swipe optical reader.
May: Kinetic Sciences demonstrates the KC-901 at the CTCT.
2000
May: Atmel unveils the FingerChip AT77C101.
May: Kinetic Sciences demonstrates a new version of their swipe optical sensor (K-1000?).

41. 2001
April: Idex & STm announce the development of SmartFinger.
Sept: Fingerprint Cards announces the FCP1030.
Nov: Citizen & IBM shows the WatchPad, the first watch with a built-in fingerprint reader, the FingerChip.
2002
Feb: Fujitsu announces the MBF300, and shows it at the CTST in May.
Summer: Tima publishes about a sweep tactile sensor.
Oct: I-Control promotes the ICS3000 / PDS3000
Nov: Authentec introduces the AES2500.
Nov: The HP iPAQ h5450 is the first PDA with a built-in fingerprint sensor, the FingerChip AT77C101 from Atmel.
Nov: STm unveils a TouchStrip prototype at the COMDEX.
2003
Feb: Alps Electrics + Casio unveiled their "rolling-tube head" scanner.
March: STm displays the TouchStrip on the web.
May: Digital Persona unveils the Firefly, a sweep optical fingerprint sensor using a roller.
Jul: Sharp announces the Mebius Muramasa, the first Tablet PC with a build-in sweep fingerprint sensor, the FingerChip.
Jul: Fujitsu announces the MBF310.
Sept: Melfas announces the MFCS1000.
Oct: YRP shows the Ubiquitous Communicator, a R&D study prototype, containing the Atrua sweep sensor.
Nov: Elsafe installs the first safe with a sweep fingerprint reader, the FingerChip.
2004
Feb: I-Control becomes Atrua and promotes "Atrua Wings" (ATW100).
Feb: Atmel announces the AT77C104, the FingerChip with integrated navigation.
Feb: Atmel announces the colored FingerChip.
Feb: The Fujitsu F900i cell phone contains the Authentec AES2500. (Japan only)
March: Upek becomes a spin-off from STm.
March: Fingerprint Cards announces the FPC1031B.
March: Validity unveils the VFS101 (USB), VFS131 (SPI) & FVS161 (LPC) (RF Fingerprint imaging on flexible tape)
March: Ritech announces the BioSlimDisk iCool containing the Upek TouchStrip.
March: Trek announces Thumdrive Swipe containing the Upek TouchStrip (to check).
April: Fujitsu announces the LOOX T series notebooks (t50H & T70H) with the Authentec AES2500.
April: Motion Computing announces the M1400 tablet PC with the Authentec AES2500.
April: MPC unveils the Transport X3000 with the Upek TouchStrip.
May: The Fujitsu F506i cell phone contains the Upek TouchStrip. (Japan only)
June: The F900it is the same as F900i, but with a twist screen.
June: The Gateway notebook 450XL contains the Upek TouchStrip.
June: Authentec announces the AES2510, a swipe sensor + navigation, available mid-June, $6.
July: The Fujitsu P7000 laptop containing the Authentec AES2500 is released. Very close from the Loox T series (the same?).
July: Texas Instrument release a DSP development board + Fingerprint Cards FPC1031. The FingerChip is scheduled 04Q3
July: A prototype of the Hitachi G1000 PDA phone containing the Atrua sensor is demonstrated in Japan.
August: The Pantech GI100 cellphone containing the Fujitsu MBF310 swipe sensor is announced.
August: LG releases the LG-LP3800 cameraphone containing the Authentec AES2500.
August: Validity unveils more info about Chip-On-Film, Module, kits...
Sep: A Lexar flash disk containing the Fujitsu MBF310 swipe sensor is released.
Sep: YRP shows a new release of the new Ubiquitous Communicator (Atrua sweep sensor?)
Oct: LighTuning announces the LTT-S500, a capacitance swipe sensor.
Nov: Jstac's Victoria 125, 126, 115, 116 hard drive with LightTuning sweep sensor.
Nov: The HP iPAQ hx2750 featuring the Atmel FingerChip AT77C104B is released.
Dec: NEC unveiled a sweep sensor prototype.
Dec: Linpo announces a flash disk with the S500 sensor from LightTuning.
Dec: The F901iC cell phone contains the Authentec swipe sensor.

42. 2005
Jan: Bionopoly unveilsBio-USB flash drive & Fingerprint Passcode Generator using the Atmel FingerChip.
Feb: IBM announces a keyboard (and peripheral) with a swipe sensor.
Feb: Atmel releases the FingerChip AT77C105
Feb: Yulong announces the Coolpad 858F GSM with the Atrua swipe fingerprint sensor.
March: Authentec unveils the Entr壆ad 1510, a swipe sensor + navigation, $5.
March: Sandisk unveils the Cruzer?Profile USB drive (using the Upek swipe sensor?).
March: IRevo introduces the Gateman MB740 door lock using the Atmel FingerChip
March: Atrua announces the ATW200. No photo.
March: G&D unveils the StarSign Bio Token containing the FingerChip sweep sensor.

43. March: The Fujitsu Stylistic ST5022 Tablet PC with the Authentec swipe sensor.
April: IBM unveils the ThinkPad X41 with the TouchStrip from Upek.
April: LG releases the LG-LP3550 cameraphone containing the Authentec AES2500.
April: Scandinavian Ecotechnologies presents a biometric card with an embedded swipe sensor likely from Fingerprint Cards.
April: Toshiba introduces the Libretto U100 with the Authentec AES2500.
April: Toshiba introduces the Portege R200 = the Dynabook SS SX/190 with the Authentec AES2500.
April: Tychi unveils the BioKnob (door knob)
April: MPC's Transport X3100 with the sweep-type Upek TouchStrip.
May: Ritech unveils the iDEA containing the Upek TouchStrip.
May: Ritech unveils the BioMouse with the Upek TouchStrip.
May: Motion Computing announces the M1600 tablet PC with the Authentec AES2500.
May: Fujitsu LifeBook S6240, S7020 & S7021 / B6000 with the Authentec swipe sensor.
June: IBM unveils the ThinkPad X41 Tablet with the TouchStrip from Upek.
June: Aratek Fingo Mouse / Fingo Reader / Fingo Lock using a swipe sensor from Authentec.
June: NEC Versa C250/M350/P550 with the Upek TouchStrip sweep sensor
June: LaCie unveils the SAFE Mobile Hard Drive using a Upek TouchStrip sensor.
June: HP nx6125 laptop with an Authentec 2501 swipe sensor.
June: Mitsumi announces an optical sweep fingerprint sensor, the SEF-A1
July: The Pantech & Curitel PT-K1200 cellphone containing an Authentec swipe sensor is unveiled.
July: Motion Computing unveils the LS800 A5 tablet PC with the Authentec AES2501.
July: Card Media announces the Storeguard with the AUthentec swipe sensor.
July: MPC's Transport T3100 with the Upek TouchStrip.
Aug: Fujitsu LifeBook P1500 with the Authentec swipe sensor.
Aug: More info about the Symwave capacitance sweep fingerprint sensor SW-6888
Aug: The Fujitsu Stylistic ST5032 Tablet PC with the Authentec swipe sensor.
Aug: Sony announces the Vaio BX series with the Upek swipe sensor.
Aug: The Lenovo ThinkPad R52 now offers a Upek fingerprint sensor (as an option).
Sep: Itronix announces the GoBook?VR-1 with the Upek swipe sensor.
Sep: Lenovo unveils the ThinkPad Z60m & Z60t with the Upek swipe sensor.
Sep: Toshiba announces the Tecra S3 M740 & M780
Sep: Willcom unveil a cellphone proto using the Fujitsu swipe fingerprint sensor.
Sep: HP released the HP iPAQ hx2790 with Windows Mobile 5.0 with the Atmel FingerChip.
Oct: Fujitsu Lifebook FMV P8210, T8210 & TB12 Tablet PCs with the Authentec swipe sensor.
Oct: Sony introduces the Vaio AX series (VGN-AX570G) with the Upek swipe sensor.
Oct: Samsung unveils the SCH S370 cellphone using the Authentec swipe sensor.
Oct: Amoi announces the M606, M616 and A717 notebook PCs with the Upek swipe sensor.
Oct: Medion introduces the MD notebook PC with the Authentec EntrePad 2501A swipe sensor.
Oct: The F902i cell phone contains the Authentec swipe sensor.
Nov: The Fujitsu P7120 laptop containing the Authentec AES2500 is released.

44. Atmel
· Official homepage of the FingerChip: Atmel website See also the (local) FingerChip products page for more information.

45. Seoul University
· A 600-dpi Capacitive Fingerprint Sensor Chip and Image-Synthesis Technique (Lee & als, Seoul National University, 1998)

46. · (2001) SmartFinger©: development with ST.
Idex
· Homepage: Idex
· (1998) IFF120: first sweep active AC capacitance sensing prototype, started with Sintef.
· (2001) SmartFinger©: development with ST.
IFF 120
SmartFinger©

47. Sannaedle / Cecrop / Kinetic Sciences
· Homepage: Cecrop/Sannaedle.
· Homepage: Kinetic Sciences (KSI).
· In 1999, Sannaedle (now Cecrop) offered a device called MyFin. At the same time, KSI offered the KC-901, which was probably the same device.
· In 2002, Cecrop was offering the CFS2000, while KSI offered the K-1000.
· In 2004, KSI is still displaying the device on their web site, while there is no more information about an optical sweep sensor on the Cecrop website.