Engineering Report Appendix 1.
Summary of Stimulus Output Test Results From the Neurometer® CPT/C and the Medi-Dx 7000.
(Click on Knob Setting links for details.)
| 2000 Hz. Frequency Setting | Neurometer® CPT/C | Medi-Dx 7000 |
| Type of Waveform Produced | Sinusoid | Undefined Pattern |
| Frequency of Stimulus Produced | 2000 Hz. | 2000 Hz. plus additional components |
| Measured Current Output | ||
| 1.50mA Knob Setting - 5K Load | 1.51 mA | 0.46 mA |
| 1.50mA Knob Setting - 10K Load | 1.49 mA | 0.34 mA |
| 9.99mA Knob Setting - 5K Load | 10.00 mA | 4.95 mA |
| 9.99mA Knob Setting - 10K Load | 10.29 mA | 3.39 mA |
| 250 Hz. Frequency Setting | Neurometer® CPT/C | Medi-Dx 7000 |
| Type of Waveform Produced | Sinusoid | Square |
| Frequency of Stimulus Produced | 250 Hz. | 173.6 Hz. |
| Measured Current Output | ||
| 1.50mA Knob Setting - 5K Load | 1.51 mA | 0.61 mA |
| 1.50mA Knob Setting - 10K Load | 1.47 mA | 0.41 mA |
| 9.99mA Knob Setting - 5K Load | 9. 86 mA | 5.55 mA |
| 9.99mA Knob Setting - 10K Load | 9.79 mA | 3.80 mA |
| 5 Hz. Frequency Setting | Neurometer® CPT/C | Medi-Dx 7000 |
| Type of Waveform Produced | Sinusoid | Undefined Pattern |
| Frequency of Stimulus Produced | 5 Hz. | 4.35 Hz. plus 2000 Hz. component |
| Measured Current Output | ||
| 1.50mA Knob Setting - 5K Load | 1.46 mA | 0.87 mA, 0.58 mA Asymmetrical Output |
| 1.50mA Knob Setting - 10K Load | 1.44 mA | 0.66 mA, 0.39 mA Asymmetrical Output |
| 9.99mA Knob Setting - 5K Load | 9.56 mA | 6.86 mA, 5.18 mA Asymmetrical Output |
| 9.99mA Knob Setting - 10K Load | 9.47 mA | 4.96 mA, 3.36 mA Asymmetrical Output |
Engineering Report Appendix 2.
Device Stimulus Output Test Directory
This Appendix details the findings of tests measuring the stimulus output of the Neurometer® CPT/C and the Medi-Dx 7000 devices. The tests were conductd over a range of loads, frequencies and intensity settings to simulate clinical usage.
A series of twelve measurements identical conditions and device settings. Tests were conducted using two different loads (5,000 Ohm and 10,000 Ohm) in order to simulate the typical impedance of skin tissue. The data was recorded using an Analogic Corporation DAS-12/50 data acquisition board for an IBM compatible PC. The specifications for this board are shown in Appendix 1. The collected data was then entered into Corel Quattro Pro® spreadsheet program for analysis and plotting. In some cases, the output voltages exceeded the input voltage range of the data acquisition board so in those cases an attenuation circuit was used to measure a reduced output voltage and the true output of the device was calculated. All circuits used are shown in Appendix 5.
Stimulus Output Tests Directory
| Test | Frequency (Hz.) | Intensity Setting (mA.) | Load (Ohms) |
| #1 | 2,000 | 1.50 | 5,000 |
| #2 | 2,000 | 9.99 | 5,000 |
| #3 | 250 | 1.50 | 5,000 |
| #4 | 250 | 9.99 | 5,000 |
| #5 | 5 | 1.50 | 5,000 |
| #6 | 5 | 9.99 | 5,000 |
| #7 | 2,000 | 1.50 | 10,000 |
| #8 | 2,000 | 9.99 | 10,000 |
| #9 | 250 | 1.50 | 10,000 |
| #10 | 250 | 9.99 | 10,000 |
| #11 | 5 | 1.50 | 10,000 |
| #12 | 5 | 9.99 | 10,000 |
Engineering Report Appendix 3.
Deviation of Stimulus Output Current from Device Intensity Settings
| 2000 Hz. Frequency | Neurometer® CPT/C | Medi-Dx 7000 |
| 1.5mA Knob Setting - 5,000 Ohm Load | + 0.7% | - 69.3% |
| 1.5mA Knob Setting - 10,000 Ohm Load | - 0.7% | - 77.3% |
| 9.99mA Knob Setting - 5,000 Ohm Load | + 0.1% | - 50.5% |
| 9.99mA Knob Setting - 10,000 Ohm Load | + 3.0% | - 66.0% |
| 250 Hz. Frequency | Neurometer® CPT/C | Medi-Dx 7000 |
| 1.5mA Knob Setting - 5,000 Ohm Load | + 0.7% | - 59.3% |
| 1.5mA Knob Setting - 10,000 Ohm Load | - 2.0% | - 72.6% |
| 9.99mA Knob Setting - 5,000 Ohm Load | - 1.3% | - 44.4% |
| 9.99mA Knob Setting - 10,000 Ohm Load | -2.0% | - 62.0% |
| 5 Hz. Frequency | Neurometer® CPT/C | Medi-Dx 7000 |
| 1.5mA Knob Setting - 5,000 Ohm Load | - 2.7% | - 42.0% / - 61.4% Asymmetric Output |
| 1.5mA Knob Setting - 10,000 Ohm Load | - 4.0% | - 56.0% / - 74.0% Asymmetric Output |
| 9.99mA Knob Setting - 5,000 Ohm Load | - 4.3% | - 31.3% / - 48.1% Asymmetric Output |
| 9.99mA Knob Setting - 10,000 Ohm Load | - 5.2% | - 50.4% / - 66.4% Asymmetric Output |
Engineering Report Appendix 4.
Ability of Each Device to Maintain A Constant Current Output
The output current from each device was measured, first while stimulating into a 5K Ohm load and then while stimulating a 10K load in order to simulate a range of skin impedances. The table below shows the percentages of the changes in output between the two test loads at two intensites at each of three frequencies of stimulus. A constant current output across a range of impedances is critical for reliable and repeatable and standardized measures.
The Neurometer® CPT/C demonstrated an ability to maintain a constant current output across all three frequencies when alternating between 5,000 Ohm and 10,000 Ohm loads with an average deviation in current output of 1.63%. The Medi-Dx 7000 did not demonstrate any ability to maintain a constant current output at any frequency when alternating between 5,000 Ohm and 10,000 Ohm loads with an average deviation in current output of 31.63%.
Changes in Current Output Intensity When
Alternating Between 5K and 10K Ohm Loads
| Neurometer® CPT/C |
Medi-Dx 7000 |
|
| 2000 Hz. @ 1.50mASetting | - 1.3% | - 26.1% |
| 2000 Hz. @ 9.99mA Setting | + 2.9% | - 31.5% |
| 250 Hz. @ 1.50mA Setting | - 2.6% | - 32.7% |
| 250 Hz. @ 9.99mA Setting | - 1.7% | - 31.5% |
| 5 Hz. @ 1.50mA Setting | - 1.3% | - 24.1% and -32.8% (Asymmetric Output) |
| 5 Hz. @ 9.99mA Setting | - 0.9% | - 27.7% and -35.1% (Asymmetric Output) |
Engineering Report Appendix 5.
Data Acquisition Equipment Used for Engineering Evaluation
Analogic Corporation DAS-12/50
Data Acquisition Board Specifications.
Engineering Report Appendix 6.
Attenuation Circuits Used for Engineering Report Measurements.
Analogic Corporation DAS-12/50
Data Acquisition Board Specifications.
