Mechanical Failure Analysis of Needles, for Micro-needle Array Dry-electrodes

 Dry electrodes, which have an array of vertically aligned conducting micro-needles over a conducting substrate/base are most suitable for long-term continuous monitoring of EEG-signal, and overcomesthe disadvantages of conventional wet electrodes. A crucial design requirement for thesemicro-needlearrays, is the choice of the needle material with suitable mechanical strength to penetrate the skin without mechanical failure. This paper gives, the results of mechanical failure analysis of different needle materials that have been typically used/proposed for invasive use. A conical needle with 150μ width at the base and 10μ width at the tip, and length in the range 10μ - 200μ was taken up for calculation. The Critical load for failure, falls in the following descending order for the selected materials: viz., Carbon Nanofibre (CNF), Titanium-alloy (Ti 6-4), Single Crystal Silicon, Nickel, Tungsten, Platinum-Iridium (Pt90 percent-Ir10 percent), Stainless Steel (SS304),Poly Methyl Methacrylate (PMMA), Polyimide, Polycarbonate, Gold, Silver, Photoresist-SU8, Polyurethane and Poly DiMethylSiloxane (PDMS).Taking the most accepted value of 0.1N as the penetration force required for needle penetration into skin, it is seen that for a needle length of 100μ, the following materials, Carbon Nanofibre (CNF), Titanium-alloy (Ti 6-4), Single Crystal Silicon, Nickel, Tungsten, Platinum -Iridium (Pt90 percent-Ir10 percent) andStainless Steel (SS304), can penetrate the skin without mechanical failure

Submarine Escape Set Test Facilities

Submarine Escape Set (SES) is used by submariners to escape from a sunken submarine. This set caters for breathing needs of the submariner under water, until he reaches the surface. Evaluation of such life-saving equipment is of paramount importance. This paper describes the submarine escape set and various constructional features and schedules of operation of test facilities designed indegenously and which can evaluate the SES. The test facility is divided into two parts: the reducer test facility, and the breathing bag test facility. The equipment has been rigorously tested and accepted by Indian Navy. Two such test facilities have been developed, one of which is installed at INS Satavahana, Visakhapatnam, and are working satisfactorily

Behaviour of ultrasonic velocities in amorphous Se<SUB>90</SUB>Ge<SUB>10</SUB> and Se<SUB>85</SUB>Ge<SUB>15</SUB> alloys near their glass transition

Precise measurements of 10 MHz frequency longitudinal and shear wave velocities are reported in amorphous SeGe alloys near their glass transition temperature Tg . There is a sharp decrease of the velocities near Tg , but the reduction in velocities appears smaller than expected

Elastic constants of sodium nitrate from 77 to 300 K

The six independent elastic constants of sodium nitrate are determined using 10 MHz ultrasonic pulse echo superposition technique over the temperature interval 77 to 300 K. The values obtained at 300 K are C<SUB>11</SUB> = 5.71, C<SUB>12</SUB> = 2.16, C<SUB>33</SUB> = 3.3, C<SUB>13</SUB> = 1.66, C<SUB>44</SUB> = 1.24, C<SUB>14</SUB> = 0.82, and at 77 K C<SUB>11</SUB> = 6.63, C<SUB>12</SUB> = 2.07, C<SUB>33</SUB> = 3.99, C<SUB>13</SUB> = 1.67, C<SUB>44</SUB> = 1.69, C<SUB>14</SUB> = 1.16 all expressed in units of 10<SUP>11</SUP> dyn/cm<SUP>2</SUP>

View the PDF document Morphometric Studies of Cytological Specimens in Breast Carcinoma using Computerised Image Analysis System .

The value of nuclear parameters were determined using interactive computer image analysis system on 100 preoperative FNAC smears of breast lesion were radical mastectomy was performed subsequently. Twenty cases of benign lesion were taken as control. The lymph node status was correlated with the nuclear and nucleolar variables. It is found that few nuclear parameters have good discriminatory power. Computerised interactive morphometry proved to be far superior to eye-piece measurements with respect to accuracy, reproducibility and time taken for parameter estimation which leads to the determination of better prognostic indicator

Computerised Image Processing and Interactive Morphometry in Cytology

Introduction of computers and image analysis systems to quantify the assessment of living cells for prognosis and diagnosis is gaining momentum. It also aims at relieving the operator from the tedium of microscopic observation and reducing operator bias and human error. This paper discusses the design and configuration of an interactive image analysis system built indigenounsly for cell analysis and classification. It also discusses the progress made in the diagnosis of cervical cancer and in the prognosis of breast cancer using computerised interactive morphometr

Ultrasonic properties in amorphous Se-P system from 300-4.2K

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Time dependence of electrical resistance at high pressure in some tellurium based amorphous alloys

Electrical resistance measurements are reported for amorphous In<SUB>20</SUB>Te<SUB>80</SUB> and Cu<SUB>25</SUB>Au<SUB>5</SUB>Te<SUB>70</SUB> alloys up to a pressure of 80 Kbar using a Bridgman anvil apparatus and a four lead arrangement to measure resistances. The amorphous samples are produced by liquisol quenching. The resistance shows time dependent changes which are analysed in detail. The contention that there is a pressure-induced transformation from the amorphous to the crystalline phase is confirmed by X-ray diffraction of samples recovered after they were pressurised to 35 Kbar in a hydrostatic environment

Elastic properties of PbS-As<SUB>2</SUB>S<SUB>3</SUB> glasses

The temperature dependence of the longitudinal and shear ultrasound wave velocities in (As<SUB>2</SUB>S<SUB>3</SUB>)<SUB>1-x</SUB>(PbS)<SUB>x</SUB> glasses has been determined from 77 to 300K using a pulse echo interferometer. Elastic constants of the prepared glasses at room temperature have been computed from the experimental data. Both longitudinal and shear ultrasound wave velocities in these glasses show a linear temperature dependence with a negative temperature coefficient