Novel instruments for remote and direct-contact laser Doppler perfusion imaging and monitoring

21 February 2002

PhD thesis defence A.N. Serov, faculty of Applied Physics, ‘Novel instruments for remote and direct-contact laser Doppler perfusion imaging and monitoring’

Novel laser Doppler instruments for establishing microcirculation in biological tissues have been developed: integrated optoelectronic probes for direct-contact blood flow measurements, and a CMOS image sensor based laser Doppler imager for remote assessment of blood perfusion in tissue. Compact design, lack of sensitivity to mechanical artifacts and a sophisticated detector geometry allowing for distinguishing of blood flow at different depths in tissue are three major advantages of the newly designed integrated probes. The novel CMOS laser Doppler imager uses a new principal of imaging technique with no moving mechanical components involved.
Also, a theoretical approach for the description of the Doppler signal on the photodetector has been developed aimed to establish correlation between the photocurrent induced by Doppler-shifted photons and scattering properties of the examined sample. The originality of this approach comprises in combination of two techniques, laser Doppler and time-varying speckle, in one uniform theory taking advantages of both.
Laser Doppler Blood Flowmetry is a non-invasive technique to measure microvascular blood flow in tissue, i.e. perfusion of the tissue by blood. The degree of blood perfusion in the cutaneous microvascular structure often provides a good indicator of peripheral vascular disease. There are many situations in routine clinical medicine where measurement of the blood flow is important: e.g. burns and plastic surgery, wound healing, dermatology, vascular and transplant surgery...
The technique depends on the Doppler principle whereby laser light incident on tissue is scattered by moving blood cells and undergoes frequency broadening. The frequency broadened laser light, together with laser light scattered from static tissue, is detected and the resulting photocurrent processed to provide a signal, which correlates with blood flow.
This research was sponsored by the Dutch Technology Foundation STW (grant no. TTN66.4358). The research has been done in cooperation with MESA+ research institute at the University of Twente, The Netherlands, and Dutch Organization for Applied Scientific Research (TNO), The Netherlands.

supervisor: prof. dr. ir. J. Greve
second supervisor: dr. ir. W. Steenbergen
information: drs. B. Meijering, telefoon (053) 489 4385