LabTrax 8/16 Hardware
The front of the LabTrax 8/16 has the analog inputs.
The back panel of the LabTrax 8/16 has four analog outputs, digital inputs or outputs, a USB port, power socket and power switch.
Lab-Trax 8/16 is the latest in data acquisition hardware. With a combined maximum sampling rate of 400ksps, it offers near simultaneous sampling on all eight channels.
- 8 channels/16 bits for recording
- Take up to 20,000 samples/second on each channel for a total of 400,000 samples every second.
MDAC is designed specifically for recording data from SI-H muscle research systems, which includes all versions of the SI-MKB and SI-CTS platforms.
MDAC Software
The MDAC program is designed specifically for recording data from SI-H muscle research systems, which includes all versions of the SI-MKB and SI-CTS platforms. This software configures the latest analog to digital recording device from WPI, the LabTrax 8/16, to provide:
Four (4) analog inputs for recording:
- Force developed by a muscle or the load placed on the muscle
- Programmed position of the motor during the lengthening or shortening of the muscle
- Actual position of the motor during lengthening or shortening of the muscle
- Other signals, like changes in membrane potentials
Two (2) analog outputs for:
- Controlling the position of the linear motor used to lengthen or shorten the muscle
- Stimulating muscles or cells directly or through a stimulus isolator connected to this output
Two (2) digital outputs for activating other devices, like pumps or cameras, at specific times during an experimental run.
Sampling and Recording Parameters
The sampling and recording parameters of the MDAC program can be customized to fit your requirements on the Preference window. Some of the parameters that can be user-specified include:
- Label on the Y-axis of each recording channel
- Conversion factor to transform voltages on each channel into the units of the measured parameters
- Offset value that centers the baseline of each channel
- Sampling frequency of the analog inputs during an experimental run
- Display time of the main data recording window
- Sampling frequency of the analog output during a position or stimulation protocol
- Location of saved data files
Channel Display Parameters
The channel display parameters of each recording channel on the main window of the MDAC program can be customized to fit your requirements through a pop-up menu for each channel. Some of the parameters that can be specified include:
- Type of plot to be displayed on each channel
- Color, line style and line width of the trace on each channel
- Style of point used to display the real data points
- Application of an anti-aliasing filter to each channel
- Method used for interpolating the regions between data points
- Type of file format used to export data
The Edit Position Protocol/Segments window shows a completed motor position protocol. As seen on the lower window, the motor is moved to specific positions at prescribed velocities by programming the voltages and duration of each segment.
The Edit Stimulation Protocol/Segments window shows a completed stimulus protocol. The stimulus voltage was increased from 0.00 to 1.00 volt (V) for duration of 19.5 seconds (sec.) after a delay of 0.50 sec.
Muscle Length Control
Some characteristics of muscles or muscle cells are quantified by performing tests on these tissues to determine parameters, like velocity of shortening or force-velocity curves. Tests that involve changing the lengths of muscles or cells quickly or gradually, or holding the tissue at a fixed length or load use a precision motor attached to one end of the tissue to change or hold its length. In tests on muscles that are loaded an additional device, like a constant load module, is required to feed information about load on the muscle back to the motor controller for adjustment of the motor’s position. Tests on unloaded muscle do not require a feedback module. In these tests, the movement of the motor and the length of the muscle are controlled directly by the MDAC program.
In MDAC, commands for moving the motor for specified distances and velocities are assembled in a series of steps, known as a position protocol, on the Edit Position Protocol window. Protocols can be composed and saved, before the experiments are conducted. For tests that do not require feedback from the force transducer, the selected position protocol controls the motor directly through a dedicated analog output. The waveforms that can be programmed into the segments of a protocol include the DC Level, Square Wave (Single/Multiple), Sine Wave, Single/Multiple), Ramp (Single/Multiple) and Staircase.
The parameters of the waveforms (segments) that can be programmed include Amplitude (V), Width (sec.), Delay (sec.), Interpulse Distance (sec.), Quantity (No.), and Beginning and Ending Amplitudes (V).
Muscle Stimulation Control
During some tests to determine the characteristics of muscle or muscle cell, the tissue needs to contract quickly (twitch) or constantly (tetanus), and in synchrony with other devices like the motor. As in position protocols, commands to create a single stimulus pulse or a train of pulses can be assembled in a series of steps, known as a stimulation protocol, on the Edit Stimulation Protocol window. As with position protocols, stimulation protocols can be composed and saved before the experiments are conducted. The waveforms that can be programmed into the segments of a protocol include DC Level, Square Wave (Single/Multiple), Sine Wave (Single/Multiple), Ramp (Single/Multiple) and Staircase.
The parameters of the waveforms (segments) that can be programmed include Amplitude (V), Width (sec.), Delay (sec.), Interpulse Distance (sec.), Quantity (No.), and Beginning and Ending Amplitudes (V).
Device Controls
During some experiments on muscle or muscle cells, additional devices, like valves or cameras, may need to be activated in synchrony with events being recorded. MDAC can be programmed to deliver a single 5V (TTL) signal, or train of these signals, to activate an external device from one of the Digital Output Protocol windows in the program. Each segment of the digital output protocol can be programmed for a HIGH (5.0V) signal to activate, or LOW (0.0V) signal to deactivate the device for specified durations (sec).
The Edit Dig Out Protocol window shows a completed digital signal. The output voltage is either set at 0.0 or 5.0V with a duration of 1 second.
Data Recording
Recording data with MDAC begins with the single click of the RECORD button on the main window. The RECORD button toggles to a STOP button as soon as recording begins. Unless a position, stimulation or digital output protocol is selected and loaded from the Protocol menu, data will continue to be recorded until you click the STOP button.
If a position, stimulation or digital output protocol is selected and loaded, data will continue to be recorded until the elapsed recording time matches the end of the protocol. If multiple protocols are selected and loaded at the same time, the data will be recorded until the elapsed recording time matches the end of the longest protocol. Combinations of protocols are limited to one of each type at the same time.
Data Export
If you prefer to analyze data using your own statistical packages, MDAC facilitates the export of data runs and files to commonly used statistical programs, like Microsoft® Excel or National Instruments’ DIAdem or as tab-delimited text file for importation into other programs. Add-on modules from National Instruments are available to simplify the export of MDAC (TDMS-format) data files to programs like Excel or Open Office Calc.
Analysis
MDAC also includes an analysis package, perfect for general purpose data processing of the sampled data. You can apply specific filter techniques (Butterworth Lowpass, Highpass, Bandpass or Bandstop filters, Savitzky-Golay polynomial filters or Moving Average filters) to smooth data or to filter unavoidable noise. Filter parameters can be selectively adjusted to your specific needs for each channel.
You may also run mathematical graphical operations like:
- Calculating the derivative of the signal (or specific points of interest).
- Integrating the signal.
- Calculating the slope values, latency, or time and voltage differences by simply positioning the cursors for each channel.
The analysis package also includes a basic statistical package that detects the minimum and maximum values, mean value, standard deviation and median value of a selected cursor region.
