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Laboratory Equipment Blog

  1. Metal Electrodes Selection Guide for Assortments and Concentric
    April 26, 2013
    Introductory Assortments Each of these assortment kits includes electrodes with different impedance within each style. Use an assortment kit to determine which electrode you need for your experiment. Each box includes the electrodes listed. There are no mix and match assortment kits. Profile A Profile B Profile C ssortments Profile A Comparison Chart 
  2. Metal Electrode Selection Guide for Profile A
    April 26, 2013
    Profile A Metal Microelectrodes Platinum Iridium These electrodes are sold in packages of 10. Order code Length Insulation Thickness Shaft Diameter Nominal Impedance ±20%
  3. Metal Electrode Selection Guide for Profile C
    April 26, 2013
    NOTE: A heat treated tip is ideal for penetrating tough membranes. (It is not recommended for chronic implantation.) This process is performed using a microforge in which the heating element is positioned in close proximity to the tip in order to melt the Parylene-C distal to the exposed metal. It provides a smooth transition and produces better adherence of the Parylene-C to the metal. Both the KT and non-KT electrodes are heat-treatable. The heat treatment is applied only to the parylene coating. The heat melts the parylene so it feathers down close to the shank near where the tip is exposed. This removes the abrupt edge where the parylene has been removed to create the tip exposure. The purpose is to prevent the parylene from delaminating from the electrode during implantation into tissue which could catch on the edge. Heat treatment does not work well in chronic applications, because the feather edge is susceptible to fluid intrusion overtime, which will alter the impedance
  4. What's the Difference Between a 3-way and 4-way Stopcock?
    April 26, 2013
    A 4-way stopcock allows for 360° of rotation and has the states (shown below) for each of the four available positions. A 3-way stopcock has only three positions and has the first three states shown below. In the first state, liquid flows between points A and B.In the second, it flows between points A and C.In the third, it flows between points B and C.In the fourth state (4-way only), it flows between all three points.    3-way and 4-way stopcocks are sold in the popular kit 14011. They can also be bought separately: 14035-10
  5. Line Up! (Reading a Vernier Scale)
    April 26, 2013
    The vernier scale was invented by French mathematician Pierre Vernier in 1631 as an upgrade on Pedro Nunes' measurement system for precision astrolobes. With a main scale and a sliding secondary scale, a vernier is used for making precise measurements.  Linear Vernier The sliding vernier scale is marked with divisions slightly smaller than the divisions of the main scale. For example, a vernier scale could have 11 markings for every 10 on the main scale. That's 10 divisions on the vernier scale for every 9 on the main scale. This means that the vernier divisions are each 90% of the main scale divisions. In this case, the 0 line and the 10 line on the vernier could pair up with marks on the main scale, but none of the other divisions on the vernier would match a line of the main scale. For example, the 0 and 10 lines of the vernier scale could pair up with the 0 and 9 lines on the main scale. If the 0 line pairs up
  6. Isolated Stimulation Explained
    April 26, 2013
    Isolated Stimulation and Stimulus Isolators The term stimulation refers to the delivery of energy of some kind to a biological tissue in order to elicit an observable response. Although the energy used in stimulation may be chemical, thermal, mechanical or electrical, this discussion will focus on electrical stimulation. Electrical stimulation of biological tissues involves the delivery of current and voltage to the stimulation site. The two quantities are related by Ohm's law: V=IR Where V is the applied voltage, I is the current and R is the electrical resistance of the tissue and or the stimulating electrodes. This simple equation shows that if voltage is constant, current flow will diminish if the tissue/electrode resistance goes up, and will increase if the resistance decreases. More commonly, the resistance of tissue differs from sample to sample, and
  7. Choosing Cables and Connectors
    April 25, 2013
    Choosing the right parts for your application is critical. Below you will find a table comparing many common parts to help you determine just what you need. Cables Order code Application/Description Connector A Connector B Cable Length 2851
  8. Micropipette Holders and Half Cells
    April 25, 2013
    WPI’s microelectrode holder-half-cells couple fluid-filled glass micropipettes to high input impedance amplifiers. A Ag/AgCl pellet (or a silver wire) molded into the holder body provides stable potential. Electrical connection is made via male 2mm pins or female 2mm sockets. The pipette may be mounted axially or at right angles to the holder. Pipettes are held with screw-caps or rubber gaskets (without caps). Filling WPI microelectrode holders with electrolytes containing chloride results in stable electrode potential. Suitable electrolytes include KCl, NaCl andCaCl2. Holders are supplied for standard WPI single capillary tubing of 1.0, 1.2, 1.5 and 2.0mm outside diameters. (Call WPI regarding custom designs for other glass diameters.) The holder style you select will depend on your experimental application, space, and instrumentation. Hints for selecting and ordering micropipette holders Determine the required electrical connection on the holder. F
  9. Precious Metals and Specialty Wire
    April 25, 2013
    WPI offers a variety of precious metals and wire. The table below compares the specifications of the various wires. The following hints are offered to help you understand the part number codes and choose the wire you need: Micro coaxial cables (MAXxxxx) are ideal for microelectrode fabrication and construction of similar research tools. The dual shielding eliminates electrical interference caused by radio frequencies (RF), electrostatic and microphonics (e.g., bending and vibration). Available with single or dual (twin) conductors. Thermocouple wire is for tem­per­a­ture mon­i­tor­ing. TCK3050 has a chromel/alumel pair, for use in inert or oxidizing atmosphere at 1500-1800 °F. Teflon-coated stainless steel (type 304) wire (SSTxxxx) is available in 25-ft and 50-ft lengths. The Teflon coating is 4µm thick. Carbon wire (C3005) is a single
  10. Physical Properties of WPI Glass Capillaries
    April 25, 2013
    The physical properties of glass depend upon the chemical composition of the glass, as well as how the glass was manufactured. Glass has no set melting point, but four temperatures are of primary importance when discussing glass production. Working Point - This is temperature that the glass is soft enough to work. At this temperature, the glass viscosity is 104 poises. Softening Point - At this temperature, glass deforms easily, even by forces of gravity. The glass viscosity is 107.6 poises. Annealing Point - When glass reaches the annealing point and remains for a few minutes, many of the internal stresses of the glass formation are obviated. During the annealing process, the glass is heated to the annealing temperature and then allowed to cool at a controlled rate. Glass that is not annealed is prone to crack or shatter with minor temperature
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