WPI Blog

Oxygen measurement is simpler than ever. Just stick a disposable, oxygen-sensitive "spot" to the inside of a flask, beaker, test tube or bottle, and fill the container with the solution to be tested. Then, on the outside of the glass container, hold the fiber optic wand close to the spot to take a reading. As the spot reacts with oxygen, it gives off light, which is measured with the fiber optic wand. This ingenious system is highly accurate and affordable. Two different units (which use the same operating principles are available: OXY-MINI and OXY-MICRO. 

You can use the PZMIV stereo microscope with a stereotaxic frame as shown in the image below. This setup shows a PZMIV-BS. The U-frame Base Plate (502045) is shown, but most stereotaxic frames can be used in this way. Choose a stereo microscope objective that allows you plenty of room to work. For example, the 0.5X objective has 187mm working distance, or the 0.32X objective has 296mm working distance. You could also add a Z-LITE-Z186 illuminator. If necessary, use a 5 to 10 lb.counter weight on the boom stand base to prevent the microscope from tipping.

WPI offers a range of biosensors for monitoring nitric oxide, hydrogen peroxide, oxygen and hydrogen sulfide. Specifications for these sensors are detailed below.

When applied to surgical instruments, Diamond-Like Carbon coating dramatically increases the life of the instrument. Because DLC-coated surgical instruments are incredibly durable and resistant to wear from chemicals, moisture and atmospheric conditions, they have a much greater useful lifespan. According to the manufacturer, pure DLC coatings as thin a 2-3μm can increase the lifespan of a pair of Vannas scissors more than 100 times that of its uncoated counterpart.

Dri-Ref™ reference electrodes were developed by WPI to have extremely low electrolyte leakage properties, hence the name “Dri-Ref.” In addition to this key feature, these electrodes exhibit stable and reproducible potential and low resistance. Stored in KCl when not in use, they have a long life expectancy. Low leakage is achieved by using KONBO™, a product combining modern ceramic and conductive polymer technology, as the liquid junction. Electrode resistance is low, an important consideration when making low-noise measurements.

When it comes to setting up microinjection systems, the options appear endless. The pictures below give some broad suggestions on how you might set up your own system. Keep in mind that many parts are interchangeable depending on your needs or preferences.

WPI's silver-silver chloride half cells are new, improved sintered pellets with lower resistance and high strength. They are stable and well-balanced in the presence of current. These small and inexpensive half-cells are easy to work with as bath electrodes.

Microscopes are a standard laboratory tool, but purchasing the right microscope for a particular application can be a challenge. First, consider how you will use the instrument. Are you looking at slides, dissecting a small animal or performing a surgery? (The application dictates the necessary working distance and power of magnification.) What kind of a stand will you be using? (Boom stand, articulating arm or post stand) Will the microscope be used in a classroom setting? (A trinocular scope offers the option of including a camera.) Will you need a camera? (A camera allows you to project the microscope image on a PC or TV or to take still images.) The answers to these questions help you determine the required working distance, level of magnification, type of mounting stand and hardware required.

Superior microelectrodes for outstanding extracellular recording — tungsten, iridium, platinum-iridium, and Elgiloy^®

WPI offers an array of metal microelectrodes. In this guide, we will look at introductory assortments, concentric electrodes, profile A, profile B and profile C electrodes. For basic information on these types of metal electrodes, see the Metal Microelectrode Basics page. Links to these related posts appear below this article.

The 14011 barbed tubing assortment kit contains over 250 items. All the items are pictured on a grid below. The darker lines in the image grid represent centimeters, and the smaller ones are 2.5mm apart.

A 4-way stopcock allows for 360 degrees 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.

Eliminate the cost and trouble of making your own micropipettes — WPI can quickly supply your need for consistently sized pre-pulled glass micropipettes for injection of dyes or proteins into cells, oocytes and for many other biomedical laboratory applications. Tip diameters (ID) range from 0.1 to 10 micrometers. Micropipettes are available as plain shank or with luer fittings.

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.

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 characteristics of the electrode unfavorably.

Use this chart for selecting Platinum Iridium metal electrodes.

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:

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.

Luer kits contain many plastic parts made of a variety of materials. A common question is how to sterilize these parts. Common sterilizing methods include:

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:

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.

In this video, WPI Chemist Nikki Scafa demonstrates how to make a PBS buffer solution for use with WPI microsensors. 

In this video, WPI Chemist Nikki Scafa demonstrates how to make a 0.1M solution of CuCl₂ for calibrating WPI NO microsensors.