Laser Doppler blood flow imaging with a 64x64 pixel full custom CMOS sensor

摘要

Full field laser Doppler perfusion imaging offers advantages over scanning laser Doppler imaging as the effects of movement artifacts are reduced. The increased frame rate allows rapid changes in blood flow to be imaged.rnA custom made CMOS sensor offers several advantages over commercial cameras as the design can be optimized to the detected signals. For example, laser Doppler signals are known to have a bandwidth from DC up to ~20KHz and be of a low modulation depth. Therefore a design that can amplify the AC component and have a sampling rate and an antialiasing filter appropriate to the signal bandwidth would be beneficial. An additional advantage of custom made sensors is that on-chip processing of blood flow allows the data bottleneck that exists between the photo-detector array and processing electronics to be overcome, as the processed data can be read out from the image sensor to a PC or display at a low data rate.rnA fully integrated 64x64 pixel array for imaging blood flow is presented. On-chip analog signal processing is used to amplify the AC component, normalize the AC signal by the DC light intensity and provide anti-aliasing. On-chip digital signal processing is used to implement the filters required to calculate blood flow.rnThe imaging array has been incorporated into a device that has been used in a clinical setting. Results are presented demonstrating changes in blood flow in occlusion and release tests.