Abstract

A 4×4 pixel array with analog on-chip processing has been fabricated within a 0.35μm complementary metal oxide semiconductor process as a prototype sensor for laser Doppler blood flow imaging. At each pixel the bandpass and frequency weighted filters necessary for processing laser Doppler blood flow signals have been designed and fabricated. Because of the space constraints of implementing an accurate ω0.5 filter at the pixel level, this has been approximated using the “roll off” of a high-pass filter with a cutoff frequency set at 10kHz. The sensor has been characterized using a modulated laser source. Fixed pattern noise is present that is demonstrated to be repeatable across the array and can be calibrated. Preliminary blood flow results on a finger before and after occlusion demonstrate that the sensor array provides the potential for a system that can be scaled to a larger number of pixels for blood flow imaging.

© 2008 Optical Society of America

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References

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  1. M. Stern, “In vivo evaluation of microcirculation by coherent light scattering,” Nature 254, 56-58 (1975).
    [CrossRef]
  2. G. Belcaro, U. Hoffman, A. Bollinger, and A. Nicolaides, Laser Doppler (Prentice Hall, 1994).
  3. W. R. Schiller, R. L. Garren, R. C. Bay, M. H. Ruddell, G. A. Holloway, A. Mohty, and C. A. Luekens, “Laser Doppler evaluation of burned hands predicts need for surgical grafting,” J. Trauma: Inj., Infect., Crit. Care 43, 35-39 (1997).
    [CrossRef]
  4. P. N. Blondeel, G. Beyens, R. Verhaeghe, K. Van Landuyt, P. Tonnard, S. J. Monstrey, and G Matton, “Doppler flowmetry in the planning of perforator flaps,” Br. J. Plastic Surg. 51, 202-209 (1998).
    [CrossRef]
  5. E. L. Speight, T. J. H. Essex, and P. M. Farr, “The study of plaques of psoriasis using a scanning laser-Doppler velocimeter,” Br. J. Dermatol. 128, 519-524 (1993).
    [CrossRef]
  6. T. J. H. Essex and P. O. Byrne, “A laser Doppler scanner for imaging blood flow in skin,” J. Biomed. Eng. 13, 189-194(1991).
    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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  15. P. E. Allen and D. R. Holberg, CMOS Analog Circuit Design (Oxford University Press, 1987).
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    [CrossRef]
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    [CrossRef]
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  22. J. Silva-Martinez and S. Solis-Bustos, “Design consideration for high performance very-low frequency filters,” in IEEE International Symposium on Circuits and Systems (1999), pp. 648-651.
  23. C. Mead, Analog VLSI and Neural Systems (Addison-Wesley, 1989).
  24. S. O. Otim, D. Joseph, B. Choubey, and S. Collins, “Modelling of high dynamic range logarithmic CMOS image sensors,” in Instrumentation and Measurement Technology Conference (2004), p. 451.

2005

2004

B. H. Pui, B. Hayes-Gill, M. Clark, M. G. Somekh, C. W. See, S. Morgan, and A. Ng, “Integration of a photodiode array and centroid processing on a single CMOS chip for a real-time Shack-Hartmann wavefront sensor,” IEEE Sens. J. 4, 787-794 (2004).

P. R. Dmochowski, B. R. Hayes-Gill, M. Clark, J. A. Crowe, M. G. Somekh, and S. P. Morgan, “Camera pixel for coherent detection of modulated light,” Electron. Lett. 40, 1403-1404(2004).
[CrossRef]

2003

S. M Park and H. J. Yoo, “2.5 Gbit/s CMOS transimpedance amplifier for optical communication applications,” Electron. Lett. 39, 211-212 (2003).
[CrossRef]

2002

B. H. Pui, B. R. Hayes-Gill, M. Clark, M. G. Somekh, C. W. See, S. P. Morgan, and A. Ng, “The design and characterisation of an optical VLSI processor for real time centroid detection,” Analog Integr. Circuits Signal Process. 32, 67-75(2002).

2001

J. D. Briers, “Laser Doppler, speckle and related techniques for blood perfusion mapping and imaging,” Physiol. Meas. 22, R35-R66 (2001).
[CrossRef]

1998

P. N. Blondeel, G. Beyens, R. Verhaeghe, K. Van Landuyt, P. Tonnard, S. J. Monstrey, and G Matton, “Doppler flowmetry in the planning of perforator flaps,” Br. J. Plastic Surg. 51, 202-209 (1998).
[CrossRef]

1997

W. R. Schiller, R. L. Garren, R. C. Bay, M. H. Ruddell, G. A. Holloway, A. Mohty, and C. A. Luekens, “Laser Doppler evaluation of burned hands predicts need for surgical grafting,” J. Trauma: Inj., Infect., Crit. Care 43, 35-39 (1997).
[CrossRef]

1993

E. L. Speight, T. J. H. Essex, and P. M. Farr, “The study of plaques of psoriasis using a scanning laser-Doppler velocimeter,” Br. J. Dermatol. 128, 519-524 (1993).
[CrossRef]

1991

T. J. H. Essex and P. O. Byrne, “A laser Doppler scanner for imaging blood flow in skin,” J. Biomed. Eng. 13, 189-194(1991).
[CrossRef]

1985

R. L. Geiger and E. Sánchez-Sinencio, “Active filter design using operational transconductance amplifiers: a tutorial,” IEEE Circuits Devices Mag. 1, 20-32 (1985).

1975

M. Stern, “In vivo evaluation of microcirculation by coherent light scattering,” Nature 254, 56-58 (1975).
[CrossRef]

Analog Integr. Circuits Signal Process.

B. H. Pui, B. R. Hayes-Gill, M. Clark, M. G. Somekh, C. W. See, S. P. Morgan, and A. Ng, “The design and characterisation of an optical VLSI processor for real time centroid detection,” Analog Integr. Circuits Signal Process. 32, 67-75(2002).

Br. J. Dermatol.

E. L. Speight, T. J. H. Essex, and P. M. Farr, “The study of plaques of psoriasis using a scanning laser-Doppler velocimeter,” Br. J. Dermatol. 128, 519-524 (1993).
[CrossRef]

Br. J. Plastic Surg.

P. N. Blondeel, G. Beyens, R. Verhaeghe, K. Van Landuyt, P. Tonnard, S. J. Monstrey, and G Matton, “Doppler flowmetry in the planning of perforator flaps,” Br. J. Plastic Surg. 51, 202-209 (1998).
[CrossRef]

Electron. Lett.

S. M Park and H. J. Yoo, “2.5 Gbit/s CMOS transimpedance amplifier for optical communication applications,” Electron. Lett. 39, 211-212 (2003).
[CrossRef]

P. R. Dmochowski, B. R. Hayes-Gill, M. Clark, J. A. Crowe, M. G. Somekh, and S. P. Morgan, “Camera pixel for coherent detection of modulated light,” Electron. Lett. 40, 1403-1404(2004).
[CrossRef]

IEEE Circuits Devices Mag.

R. L. Geiger and E. Sánchez-Sinencio, “Active filter design using operational transconductance amplifiers: a tutorial,” IEEE Circuits Devices Mag. 1, 20-32 (1985).

IEEE Sens. J.

B. H. Pui, B. Hayes-Gill, M. Clark, M. G. Somekh, C. W. See, S. Morgan, and A. Ng, “Integration of a photodiode array and centroid processing on a single CMOS chip for a real-time Shack-Hartmann wavefront sensor,” IEEE Sens. J. 4, 787-794 (2004).

J. Biomed. Eng.

T. J. H. Essex and P. O. Byrne, “A laser Doppler scanner for imaging blood flow in skin,” J. Biomed. Eng. 13, 189-194(1991).
[CrossRef]

J. Trauma: Inj., Infect., Crit. Care

W. R. Schiller, R. L. Garren, R. C. Bay, M. H. Ruddell, G. A. Holloway, A. Mohty, and C. A. Luekens, “Laser Doppler evaluation of burned hands predicts need for surgical grafting,” J. Trauma: Inj., Infect., Crit. Care 43, 35-39 (1997).
[CrossRef]

Nature

M. Stern, “In vivo evaluation of microcirculation by coherent light scattering,” Nature 254, 56-58 (1975).
[CrossRef]

Opt. Express

Physiol. Meas.

J. D. Briers, “Laser Doppler, speckle and related techniques for blood perfusion mapping and imaging,” Physiol. Meas. 22, R35-R66 (2001).
[CrossRef]

Other

G. Belcaro, U. Hoffman, A. Bollinger, and A. Nicolaides, Laser Doppler (Prentice Hall, 1994).

B. H. Pui, B. R. Hayes-Gill, M. Clark, M. Somekh, C. W. See, S. Morgan, and A. Ng, “The design of a real time VLSI optical centroid processor,” in Proceedings of IEEE Sensors 2002 (IEEE, 2002) Vol. 1, pp. 5-10, doi: 10.1109/ICSENS.2002-1036974.

C. Kongsavatsak, “Full field laser Doppler blood flow camera,” Ph.D. dissertation (University of Nottingham, U.K., 2005).

A. Moini, Vision Chips (Kluwer Academic, 2000).

P. E. Allen and D. R. Holberg, CMOS Analog Circuit Design (Oxford University Press, 1987).

F. Irons, Active Filters (Artech House, 2005).

R. L. Geiger, P. E. Allen, and N. R. Strader, VLSI Design Techniques for Analog and Digital Circuits (McGraw-Hill, 1990).

B. Razavi, Design of Analog CMOS Integrated Circuits (McGraw-Hill, 2001).

J. Silva-Martinez and S. Solis-Bustos, “Design consideration for high performance very-low frequency filters,” in IEEE International Symposium on Circuits and Systems (1999), pp. 648-651.

C. Mead, Analog VLSI and Neural Systems (Addison-Wesley, 1989).

S. O. Otim, D. Joseph, B. Choubey, and S. Collins, “Modelling of high dynamic range logarithmic CMOS image sensors,” in Instrumentation and Measurement Technology Conference (2004), p. 451.

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Figures (10)

Fig. 1
Fig. 1

Block diagram of (a) the overall 4 × 4 array and (b) a single pixel within the array (HPF—high-pass filter, FWF—frequency weighted filter, RS0, RS1—row select, CS0, CS1—column select, MUX—multiplexer, Conc—concentration, RGC—regulated cascode transimpedance amplifier, HDA—hysteretic differential amplifier).

Fig. 2
Fig. 2

Front-end design: (a) basic logarithmic front end, (b) RGC front end, and (c) comparison of bandwidth for different dc photocurrents (simulated).

Fig. 3
Fig. 3

Schematic of OTA-C based filters: (a) bandpass and (c) frequency weighted. Comparison of simulated and measured responses: (b) bandpass and (d) frequency weighted.

Fig. 4
Fig. 4

(a) Layout of each pixel and (b) layout of a 4 × 4 array.

Fig. 5
Fig. 5

Optical configuration of (a) sensor characterization setup and (b) in vivo imaging.

Fig. 6
Fig. 6

Concentration maps obtained using sensor characterizing system for different modulation frequencies and modulation depths with dc fixed.

Fig. 7
Fig. 7

Flow maps obtained using a chip characterizing system for different modulation frequencies and modulation depths.

Fig. 8
Fig. 8

Mean concentration (a), (b) and flow (c), (d) for a range of frequencies at two different modulation depths. The error bars represent the standard deviation of the values across the 16 pixels of the array.

Fig. 9
Fig. 9

Single pixel measurements on an occluded and nonoccluded human finger and static tissue: (a) concentration and (b) flow. There is a 5 s interval between the measurements on each sample.

Fig. 10
Fig. 10

Concentration (a), (b) and flow (c), (d) maps after occlusions (a), (c) and after cessation of occlusion (b), (d).

Equations (5)

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Gain ( subthreshold ) = 1 g m = n U T I dc ,
I dc = m · i ac ,
v ac = i ac · 1 g m = I dc m n U T I dc = n m U T .
B W front end = g m 2 π C p = I dc 2 π n U T C p ,
f cutoff = G m 2 π C ,

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