The fundamental limitations of photoacoustic microscopy for detecting optically absorbing molecules are investigated both theoretically and experimentally. We experimentally demonstrate noise-equivalent detection sensitivities of 160,000 methylene blue molecules (270 zeptomol or 2.7×10-19  mol) and 86,000 oxygenated hemoglobin molecules (140 zeptomol) using narrowband continuous-wave photoacous...

Nitric oxide has been proposed to be transported by hemoglobin as a third respiratory gas and to elicit vasodilation by an oxygen-linked (allosteric) mechanism. For hemoglobin to transport nitric oxide bioactivity it must capture nitric oxide as iron nitrosyl hemoglobin rather than destroy it by dioxygenation. Once bound to the heme iron, nitric oxide has been reported to migrate reversibly fro...

Background: Serial blood draws for the assessment of a trauma patient’s hemoglobin (sHgb) and hematocrit (sHct) is standard practice. In the event of multiple casualties this process can be time consuming and lead to the inefficient use of valuable resources. A device that would allow for continuous real-time, non-invasive monitoring of hemoglobin and tissue perfusion would not only improve the...

Freshly prepared hemoglobin solutions were successively irradiated up to five times with 1 MW (monochromatic wavelength) of green (530 mmicro) laser power. Oxygenated hemoglobin showed no detectable change, but the spectral absorption of reduced hemoglobin showed a shift toward the characteristic curve for the oxygenated form. Intact human erythrocytes exposed to a power density of 110 MW/cm(2)...

Multi-channel functional near infrared topography (fNIRT) is a non-harmful, non-invasive and safe optical imaging technique that allows the simultaneous acquisition of oxygenated and deoxygenated hemoglobin concentration changes on the scalp. This study was aimed at investigating the potential use of fNIRT in association with a cognitive system, namely the working memory, for brain-computer int...

OBJECTIVE Coronary artery bypass grafting with cardiopulmonary bypass carries a risk for neurologic complications because of cerebral hypoperfusion and microembolization. The basic goals of a novel closed minimized extracorporeal circulation are to prevent excessive hemodilution and to avoid blood-air interface. The aim of this prospective randomized study was to determine the effect of using t...

We report on the scattering properties of oxygenated and deoxygenated whole blood from 250 to 1000 nm. We determine the complex refractive index of oxygenated and deoxygenated hemoglobin using a Kramers-Kronig analysis and optical coherence tomography measurements. Combining these data with Mie theory, the scattering properties are calculated. The strong oxygen saturation dependent scattering e...

Pulse oximetry measures the relative concentration of arterial oxygenated hemoglobin and reduced hemoglobin. This paper presents the design of a pulse oximeter, which measures the presence of a third substance, carboxyhemoglobin (HbCO), by unfiltered LEDs at 660 nm, 810 nm, and 940 nm. Background information is given on the theory of pulse oximetry. Theoretical approximations and calculations w...