Endoscopic Optical Doppler Tomography Based on Two-Axis Scanning MEMS Mirror

We study the feasibility of endoscopic optical Doppler tomography with a micro-electro-mechanical system(MEMS) mirror based probe. The additional phase shifts introduced by the probe are tracked and formulated.The suppression method of the probe phase shifts is proposed and validated by fluid flow detection experiments.In vivo blood flow detection is also implemented on a hairless mouse. The velocities of the blood flow in two directions are obtained to be-8.1 mm/s and 6.6 mm/s, respectively.

Optical coherence tomography of the living human kidney

Acute tubular necrosis(ATN)induced by ischemia is the most common insult to donor kidneysdestined for trarsplantation.ATN results from sweling and subsequent damage to cells lining thelkidney tubules.In this study,we demonstrate the capability of optical coherence tomography(OcT)to image the renal microst ructures of living human donor kidneys and potentially providea measure to det ermine the extent of A TN.We also found that Doppler-based OCT(i.e.,DOCT)reveals renal blood flow dynamics that is another major factor which could relate to post-transplant renal finction.All OCT/DoCT oberva tions were performed in a noninvasive,sterileand timely manner on intact human kidneys both prior to(er vivo)and following(in vivo)theirtransplantation.Our results indicate that this imaging model provides transplant surgeons withan objective visualization of the transplant lidneys prior and immediately post transplantation.

SIMULATION AND MEASUREMENT OF FLOW FIELD IN MICROCHIP

Cancer(malignant tumor)is one of the serious threats to human life,causing 13%of all human deaths.A crucial step in the metastasis cascade of cancer is hematogenous spreading of tumor cells from a primary tumor.Thus,isolation and identification of cells that have detached from the primary tumor and circulating in the bloodstream(circulating tumor cells,CTCs)is considered to be a potential alternation to detect,characterize,and monitor cancer.Current methods for isolating CTCs are limited to complex analytic approaches that generate very low yield and purity.Here,we propose a high throughput 3D structured microfluidic chip integrated with surface plasmon resonance(SPR)sensor to isolate and identify CTCs from peripheral whole blood sample.The microfluidic velocity-field within the channel of the chip is mediated by an array of microposts protruding from upper surface of the channel.The height of microposts is shorter than that of the channel,forming a gap between the microposts and the lower surface of the channel.The lower surface of the channel also acts as the SPR sensor which can be used to identify isolated CTCs.Microfluidic velocity-field under different parameters of the arrayed microposts is studied through numerical simulation based on finite element method.Measurement on one of such fabricated microchips is conducted by our established optical Doppler tomography technique benefiting from its noninvasive,noncontact,and high-resolution spatialresolved capabilities.Both simulation and measurement of the microfluidic velocity-field within the structured channel demonstrates that it is feasible to introduce fluidic mixing and causes perpendicular flow component to the lower surface of the channel by the 3D structured microposts.Such mixing and approaching capabilities are especially desirable for isolation and identification of CTCs at the coated SPR sensor.

THE EXPERIMENTAL STUDY OF STRESS-RELATED PATHOLOGICAL CHANGES IN CEREBRAL VENOUS BLOOD FLOW IN NEWBORN RATS ASSESSED BY DOCT

In experiments on newbom rats with stress related intracrani al hemorhage(ICH)using Doppler optical coberence tomognaphy(DOCT)we have shown that latent stage of ICH(4 h after stress)is characterized by decrease of venous blood outflow and the loss of sensitivity of sagittal vein to vasoconstrictor ffect of adrenaline.The incidence of ICH(24 h after stress)was accompanied by progressi on of early pathological changes in cerebral venous blood flow(CVBF)and development of venous insufficiency.Taking into consideration of this fact,we suggest that the suppression of CVBF related to the severity to the deleterious effect of stress on the brain hemodynamics in newborn rats.These facts allow us to conclude that the venous insufficiency with the loss of vasoconstrictor response to adrenaline is an informative and sensitive component of pattern of CVBF that can be important diagnostic criteria of risk of ICH development in newborns.