Near infrared (NIR) light in the wavelength range from 700 to 900 nm can pass through skin, bone and other tissues relatively easily. As a result, NIR techniques allow a noninvasive assessment of hemoglobin saturation for a wide range of applications, such as in the study of muscle metabolism, the diagnosis of vascular disorders, brain imaging, and breast cancer detection. Near infrared Spectroscopy (NIRS) is an effective tool to measure the hemoglobin concentration in the tissues, which can discriminate optically the oxy- and deoxy- hemoglobin species because of their different near-infrared absorption spectra.
We have developed an NIRS probe consisting of a laser diode of 830 nm wavelength and a PIN photodiode in reflectance mode. We have selected a set of healthy volunteers (mean age 30, range 26-40 years) for the study. The probe is placed on forearm of each subject and the backscattered light intensity is measured by occluding the blood flow at 210, 110 and 85 mmHg pressures. Recovery time, peak time and time after 50% release of the cuff pressure are determined from the optical densities during the post occlusive state of forearm.
These parameters are useful for determining the transient increase in blood flow after the release of blood occlusion. Clinically, the functional aspects of blood flow in the limbs could be evaluated noninvasively by NIRS.
Electromechanical sensors and actuators are important for robotic and aerospace applications. Among various material, poly(vinylidene fluoride) ir its co-polymers are known to exhibit high piezosensitivity. However, due to their higher electrical resistivity the input impedance of subsequent signal processign circuits is required to be very high. A novel technique to decrease the impedance would be blending PVDF with conducting polyaniline (PANI) but without affecting the piezosensitivyt of PVDF. Polyaniline (PANI) was synthesized by well known standard chemical route using dopants HCl and dodecyl benzene sulfonic acid. These PANI powder were blended with PVDF which was first dissolved in DMAc at 50 degrees C to which were added requisite amounts of two types of PANI ranging from 2 to 25 wt percent, stirred for 24 hours to form a homogeneous mixture which was cast in glass petri-dish, followed by complete solvent evaporation at 50 degrees C and then drying under vacuum for 24 hours to give films of PANI-PVDF blends. The piezo-sensitivity of these blends was measured before and after poling in electrical field. The sensitivity factor was dependent on the composition, type of dopant as well as the electric polarization of the blend. The HCl doped PANI blends in PVDF were highly piezo-sensitive than other blend compositions. These various results have been explained on the basis of compatibility, discrete domain formation, nonlinear conduction process for charge transport, orientation of dipoles, and trapping of space charge at inter-domain sites.
The total amount of light reflected by any portion of a smooth mirror-like surface remains the same before and after deformation. From this observation, if two intensity records of images reflected from the surface of a plate before and after loading are available, the shift of any image point due to loading is estimated by an intensity integration technique (IIT). This enables mapping of surface slope and curvature for the entire plate. The experimental values for slope and mean values for curvature by this technique agree to within 8 - 10% of the theoretical values. If the plate contains a defect the local values of curvature vary sharply. The intensity can be shown related directly to curvature and so the intensity record of the loaded defective plate displays noticeable abrupt changes in the region of defect, thus opening up possibilities for Non-Destructive Testing (NDT).
Conference Committee Involvement (5)
Electroactive Polymer Actuators and Devices (EAPAD) XII
8 March 2010 | San Diego, California, United States
Electroactive Polymer Actuators and Devices (EAPAD) XI
9 March 2009 | San Diego, California, United States
Electroactive Polymer Actuators and Devices (EAPAD) X
10 March 2008 | San Diego, California, United States
EAP Actuators and Devices (EAPAD)
19 March 2007 | San Diego, California, United States
Electroactive Polymer Actuators and Devices (EAPAD)
27 February 2006 | San Diego, California, United States