Broadband dielectric spectroscopy on human blood

Terahertz time-domain spectroscopy of human blood

In the continuing development of terahertz technology to enable the determination of tissue pathologies in real-time during surgical procedures, it is important to distinguish the measured terahertz signal from biomaterials and fluids, such as blood, which may mask the signal from tissues of interest. In this paper, we present the frequency-dependent absorption coefficients, refractive indices, and Debye relaxation times of whole blood, red blood cells, plasma, and a thrombus.

Microwaving blood as a non-destructive technique for haemoglobin measurements on microlitre samples

The non-destructive ex vivo determination of haemoglobin (Hgb) concentration offers the capability to conduct multiple red blood cell haematological measurements on a single sample, an advantage that current optical techniques are unable to offer. Here, a microwave method and device for the accurate and non-destructive determination of Hgb concentration in microlitre blood samples are described. Using broadband microwave spectroscopy, a relationship is established between the dielectric properties of murine blood and Hgb concentration that is utilized to create a technique for the determination of Hgb concentration. Subsequently, a microwave dielectric resonator-microfluidic system is implemented in the analysis of 52 murine samples with microlitre volumes and Hgb concentrations ranging from 0 to 17 g dL(-1) . Using the characterized relationship, independent and minimally invasive Hgb measurements are made on nine healthy mice as well as seven with mutations in the Adenomatous polyposis coli (APC) gene that leads to colorectal cancer and consequently anaemia.

Dynamics of supercooled water in a biological model system of the amino acid l-lysine

Lysine solutions establish a new relaxation behaviour of supercooled interfacial water.

On a different approach toward low-frequency dielectric spectroscopy measurements of conductive liquids

Driven by recent interest in the low-frequency Debye-like relaxations in hydrogen bonding liquids, here we present an alternative method for measuring such relaxations without the detrimental effects of ionic conductivity or electrode polarization. Glycerol was chosen as a molecule of interest, and a fit for the α-transition using the Vogel-Fulcher-Tammann equation was found to be τ = 2.31 × 10(-14) exp(2110 K∕[T-135 K]). This method is easily adaptable by most laboratories with existing dielectric spectrometers, and could prove useful in the accurate measurement of relaxations in conductive media at low frequencies. A brief summary of comparable techniques is also presented.

Terahertz time-domain spectroscopy of human blood

In the continuing development of terahertz technology to enable the determination of tissue pathologies in real-time during surgical procedures, it is important to distinguish the measured terahertz signal from biomaterials and fluids, such as blood, which may mask the signal from tissues of interest. In this paper, we present the frequency-dependent absorption coefficients, refractive indices, and Debye relaxation times of whole blood, red blood cells, plasma, and a thrombus.

Erythrocyte swelling and membrane hole formation in hypotonic media as studied by conductometry

Hypoosmotic swelling of erythrocytes and the formation of membrane holes were studied by measuring the dc conductance (G). In accordance with the theoretical predictions, these processes are manifested by a decrease in G followed by its increase. Thus, unlike the conventional osmotic fragility test, the proposed methodological approach allows investigations of both the kinetics of swelling and the erythrocyte fragility. It is shown that the initial rate of swelling and the equilibrium size of the cells are affected by the tonicity of a hypotonic solution and the membrane rheological properties. Because the rupture of biological membranes is a stochastic process, a time-dependent increase in the conductance follows an integral distribution function of the membrane lifetime. The main conclusion which stems from reported results is that information about rheological properties of red blood cell (RBC) membranes and the resistivity of RBCs to a certain osmotic shock may be extracted from conductance signals.