Interfacing in Biology
Probes and Sensors
You may want to consider the following probes for the biology
lab.
(Click here for suggested uses for
these probes in biology)
Vernier Software makes
other sensors and probes for use with the interfacing equipment.
A brief description of all of the available probes can be found
here.
What to purchase
This is not an easy answer, since different people do different
things in the lab. I suggest purchasing sensors and probes necessary
to do the labs you want to do. Make a list of the labs you want to perform or design. Examine books that have an assortment of labs already written. Select the labs you are most interested in and count the number of times a certain probe will be necessary. I find the temperature, pH, and pressure (Bio-Gas?) sensors extremely useful.
TI sensors and probes?
Several probes and sensors are designed exclusively for the CBL
system, including a temperature probe, a light sensor, a microphone,
and a motion sensor. These are automatically
recognized by the CBL and do not require any adapter.
Note that almost all of the Vernier sensors and probes can be
used with the CBL if you purchase a CBL-DIN adapter (very inexpensive).
This adapter does not ship with the CBL (neither does an AC adapter).
I would recommend having 3 or 4 CBL-DIN adapters per CBL unit.
You will need to write or obtain a program for
the CBL system to perform most experiments.
Probe and Sensor List
Specifications, tips for use, and prices of several probes can
be found below.
The pressure range is 24 to 32 inches of Hg (0.8 to 1.05 atm)
absolute pressure. Do not get this probe wet!
Water inside the box will ruin it. This sensor connects to a 3-way
valve using plastic tubing.
Order Code BAR-DIN $56.00
The Biology Gas Pressure Sensor is a new sensor that may replace
the need for purchasing either a Pressure sensor or a Barometer.
It combines the resolution of the barometer with the range most
biology teachers require (0.7 - 1.5 atm). Do not get this probe
wet! Water inside the box will ruin it. This sensor connects to
a 3-way valve using plastic tubing.
This is a 3-color (red-635 nm, green-565 nm, blue-470 nm) colorimeter.
It is great for determining the concentration of unknown solutions,
or studying changes in concentration vs. time. Fifteen 3.5-mL
cuvettes are included. (A package of 100 replacement cuvettes
is available.
Order Code COL-DIN $99.00
This probe is great for environmental testing of water samples
for salinity, total dissolved solids (TDS), or conductivity. Biology
teachers can use this probe to demonstrate the migration of ions
through membranes or to monitor changes in ion levels (such as
HCO3-) in aquatic systems.
You can take readings in units of conductivity (S/cm) or concentration
(mg/L and ppm as TDS or NaCl). The Conductivity Probe can monitor
conductivity at three different sensitivity settings:
- 0-100 mg/L TDS or 0-200 S
- 0-1000 mg/L TDS or 0-2000 S
- 0-5000 mg/L TDS or 0-10,000 S
Conductivity is directly proportional to concentration over the
entire range.
The probe will reach 98% of full value in less than 10 seconds.
A known standard (500 mg/L solution is provided for easy calibration.
This probe is rugged and will not electrolyze solutions, as it
uses alternating current.
Conductivity Probe (incl. probe, amplifier,500mg/L calibration
solution). Order Code CON-DIN $79.00
Make fast, accurate measurements of dissolved oxygen in water
samples using the Dissolved Oxygen Probe. This probe features:
- Range: 0-20 mg/L (ppm) of dissolved oxygen.
- Built-in temperature compensation, which means you can do
your calibrations in the lab, and then make measurements outdoors
without having to recalibrate.
- Fast response time, reaching 95% of full reading in 30 seconds.
- Pre-fit membranes. It's easy to change membranes on the dissolved
oxygen probe. Disposable caps with pre-fit membranes allow one
to quickly and conveniently change membranes. Two membrane caps
are included.
- Calibration: Simply place the electrode in the zero-oxygen
solution provided with the probe for the 0% calibration point.
For the 100% calibration point, place the electrode in air (or
better yet, in water-saturated air, using a sealable bottle that
is provided). You will need the barometric pressure and temperature
of the room to look up the concentration of oxygen at saturation.
The electrode can be calibrated in any units you choose: % D.O.,
mg/L, or ppm dissolved oxygen.
This probe requires a warm-up period of 30 minutes. If you use
this with a CBL system, be sure to use an AC adapter during warm-up,
or the unit may need new batteries in the field!
The DO-DIN includes the DO probe, amplification box, zero-oxygen
solution, two membrane caps, a 100% calibration bottle, electrode
filling solution, and a probe information booklet. Replacement
caps are available.
Order Code DO-DIN $189.00; Replacement Membranes Order Code
MEM $9.50
A small ear clip is provided. An IBM, Macintosh, or Apple II Heart
Rate Monitor Program is included if you are using this sensor
with a computer. The Heart Rate Monitor Program displays a pattern
representing your heart rhythm. It also displays the heart rate
in beats/minute in large digits.
Order Code HRM-DIN $47.00
The Light Sensor approximates the human eye in spectral response
and can be used over three different illumination ranges, selected
with a switch. The ranges are 0-600, 0-6000, 0-150,000 lux.
Order Code LS-DIN $39.00
This sensor, which uses a Hall Effect transducer, is sensitive
enough to measure the earth's magnetic field. Its two ranges are
3.2 gauss ( 3.2 x 10-4 tesla) and 64 gauss ( 6.4 x 10-3 tesla).
Order Code MG-DIN $44.00
Vernier Software manufactures two types of microphones. The microphone
to get plugs into an interface and can be used for waveform and
periodic function studies.
The ULI Microphone/Amplifier (MCA-U) is designed for the ULI interface.
While this microphone may also be used with the MPLI or the CBL
(using CBL-DIN adapter), there are other microphones designed
specifically for these interfaces.
The MPLI Microphone/Amplifier (MCA-M) is designed for the PC's
MPLI interface.. This microphone may be used with the CBL by using
the CBL-8MC adapter.
The CBL Microphone/Amplifier (MCA-CBL)
is a combination of the MCA-U and MCA-M. This was made to provide
one microphone that could be used on either of the CBL input ranges
(0 to 5V or -10 to +10V). This microphone plugs directly into
the CBL without the need for an adapter.
Order Code MCA-U $30.00 (for use with ULI ); Order Code MCA-M
$30.00 (for use with MPLI); Order Code MCA-CBL $30.00 (for use
with CBL System)
The Motion Detector is like the automatic range finder on a Polaroid
camera. This is the same type of sensor that is also known as
a "sonic ranger" or "ultrasonic motion detector".
This sonar device emits ultrasonic pulses that reflect off objects
in their path. The time it takes for the reflected pulses to return
is used to calculate distance, velocity, and acceleration. The
range of the sensor is 0.5 to 6.0 meters. We offer the same detector
with different connectors for specific interfaces.
Order Code MD-CBL $64.00 (for use with
CBL System); Order Code U-MD $65.00 (for use with ULI or CBL
and CBL-RJ11 adapter); Order Code MD-M $66.00 (for use with MPLI
or CBL and CBL-8MD adapter)
The pH System consists of a pH Electrode and pH Amplifier. The
pH Electrode is an Ag-AgCl combination electrode with a range
of 0 to 13 pH. The pH Amplifier contains the signal-conditioning
circuitry. The pH Amplifier and pH Electrode are also available
separately.
pH System - includes amplifier and electrode. Order Code PH-DIN
$72.00; pH Amplifier only. Order Code PHA-DIN $40.00; pH Electrode
only. Order Code 7120B $32.00; pH Buffer Capsules. Order Code
PHB $10.00
The Pressure Sensor has a range of 0 to 100 psi (0 to 6.8 atm)
absolute pressure. Do not get this probe wet! Water inside the
box will ruin it. Plastic tubing connects to a 3-way valve. Older
sensors have a metal valve, while newer sensors have a plastic
valve. I prefer the plastic valves - they are sturdy and very
easy to control.
Order Code PS-DIN $60.00
The Radiation Monitor consists of a Geiger-Mueller tube and rate
meter mounted in a small, rugged, plastic case. The unit is battery
operated and can be used without a computer for measurement of
alpha, beta, and gamma radiation from background sources. It can
be used with a ULI and the Event Counter software to explore radiation
statistics, measure the rate of nuclear decay, and monitor radon
daughters.
Compatible Interfaces: Universal Lab Interface (ULI)
Order Code U-RM $190.00
The Relative Humidity Sensor contains an integrated circuit that
can be used to monitor relative humidity over the range 0 to 95%
(+/- 5%). Unlike the barometer and pressure sensors, this sensor
must be placed in the environment being measured. A plastic tube
does not connect the sensor to the air.
Order Code RH-DIN $62.00
Vernier Software manufactures a variety of temperature probes
for use with various interfaces.
The Direct-Connect Temperature Probe is the low-cost way
to measure temperature. The probe has a brass tube with a temperature
sensor at the end. The tube is covered with Teflon heat-shrink
tubing to make it resistant to chemicals. It plugs directly into
any of the interfaces. The temperature range is -15 to +110 degrees
C (+/- 0.2 degrees C in normal use). This probe cannot easily
be used together with a DO probe, conductivity probe, or pH probe
in the same solution, if the probes are attached to the same interface.
To use it, wrap the probe in waran wrap to electrically insulate
it from the water. It is, however, my preferred temperature probe.
The Standard Temperature Probe is a rugged, general-purpose
laboratory temperature probe. The probe consists of a brass tube
with a sensor at the end. The tube is covered with Teflon heat-shrink
tubing to make it resistant to chemicals. The probe plugs into
a small box which contains the signal-conditioning circuitry.
The temperature range: -50 to +150 degrees C (0.2 degrees C in
normal use). This probe can be used together with a DO probe,
conductivity probe, or pH probe in the same solution, when the
probes are attached to the same interface.
The Quick-Response Temperature Probe is electronically
the same as the Standard Temperature Probe, but the sensor is
in a smaller, ceramic package. The result is that the probe responds
to changes in temperature much faster, but is less protected,
both chemically and physically. Recommended for use in air and
water only. The temperature range: -50 to +150 degrees C (+/-
0.2 degrees C in normal use).
The Thermocouple uses type-K thermocouple wire to measure
the difference in temperature between its two junctions. It can
be used over the range -200 to 1400 degrees C (+/- 10 degrees
C). It is great for studying flame temperatures.
Direct Connect Temperature Probe DCT-DIN $25.00; Standard
Temperature Probe TPA-DIN $43.00; Quick Response Temperature Probe
TPAQ-DIN $49.00; Thermocouple TCA-DIN $35.00
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