Grass S88X User and Service Manual Release D

Publisher’s Notice Natus Medical Incorporated DBA Excel-Tech Ltd. (XLTEK) 2568 Bristol Circle Oakville, ON L6H 5S1 Canada phone: +1 401.773.2600 fax: +1 401.732.7097 toll-free: 1.877.472.7779 (USA only), 1.855.554.3184 (Canada only) email: [email protected] www.natus.com EUROPEAN AUTHORIZED REPRESENTATIVE: Natus Europe GmbH Robert-Koch-Str. 1 82152 Planegg Germany

© Copyright 2013 by Excel-Tech Ltd. (XLTEK) The information in this publication is provided for reference only. All information contained in this publication is believed to be correct and complete. Excel-Tech Ltd. shall not be liable for errors contained herein nor for incidental or consequential damages in connection with the furnishing, performance, or use of this material. All product specifications, as well as the information contained in this publication, are subject to change without notice. This publication may contain or reference information and products protected by copyrights or patents and does not convey any license under the patent rights of Excel-Tech Ltd., nor the rights of others. Excel-Tech Ltd does not assume any liability arising out of any infringements of patents or other rights of third parties. All rights reserved. This document contains confidential or proprietary information of Excel-Tech Ltd. No part of this document may be reproduced or transmitted in any form or by any means without the written permission of Excel-Tech Ltd. Excel-Tech Ltd. makes no warranty of any kind with regard to this material, including but not limited to the implied warranties of merchantability and fitness of a particular purpose.

Trademarks AURA®, Comet-PLUS®, EC2®, FASS®, Grass®, Grass Technologies®, Neurotrac®, Panorama®, SleepTrek®, SzAC®, TWin®, TWinLOOK® and TREA® are trademarks of Natus Medical Incorporated. Other brand and product names are trademarks or registered trademarks of their representative holders.

Printed in the United States of America

Important This manual is subject to periodic review, update, and revision. Customers are cautioned to verify that the manual’s information applies to the software and hardware present in the equipment. This product performs as described in this manual, and in accompanying labels and/or inserts, when assembled, operated, maintained, and repaired in accordance with the instructions provided. This product must be cleaned and checked periodically. Do not use a defective product. Parts that are broken, missing, worn, or contaminated should be replaced immediately. If repair or replacement becomes necessary, call or write to request service advice from Grass. This product must not be altered without the prior written approval of Grass. The user of this product shall have the sole responsibility for any malfunction that results from improper use, faulty maintenance, improper repair, unauthorized service, or alteration by anyone other than Grass. The safety, reliability, and performance of this device can only be assured under the following conditions: • If the device has been used according to the accompanying operating instructions. • If changes or repairs have been carried out by Grass. • If it is used in buildings having ground equalization wiring that complies with relevant UL, CSA, IEC or other local standards and regulations.

Intended Use The S88X Stimulator is a general purpose, electrical stimulator for nerve and muscle that has a wide range of parameters to satisfy a wide range of research applications. FOR USE BY QUALIFIED PERSONS ONLY. NOT INTENDED FOR THERAPEUTIC PURPOSES.

Warnings READ THIS BEFORE OPERATING S88X The available voltage and current from this Stimulator may, under some conditions, be sufficient to be lethal or cause burns, particularly with high duration and/or high voltage settings. It is the responsibility of the investigator/user, to determine for any given application, the maximum safe levels of stimulation, and assure that such stimulation levels will not be exceeded. In many applications, the mechanisms of safe stimulation are not completely understood. Parameters that affect safe stimulation levels are: • Pulse Repetition Rate • Pulse Duration • Pulse Duty Cycle • Voltage and/or Current Intensity • Biphasic vs Monophasic Operation • Total Time Exposure • Electrode Impedance, Geometry, Area and Material The S88X OUTPUT is NOT ISOLATED. Do not use on humans. CONSULT GRASS IF YOU HAVE ANY CONCERNS ABOUT SAFE APPLICATION, PARTICULARLY WHEN USED WITH OTHER EQUIPMENT. NATUS MEDICAL INCORPORATED WAIVES THE RESPONSIBILITY WHATSOEVER FOR ANY INJURIES INCURRED TO THE OPERATOR OF THIS INSTRUMENT, OR TO ANY ANIMAL OR HUMAN SUBJECT AS A RESULT OF THE IMPROPER USE AND/OR ABUSE OF THIS STIMULATOR.

Table of Contents 1. Specifications & Symbols Glossary... 1-11 Specifications. ...1-11 Glossary of Symbols...1-12 2. Introduction... 2-13 Safety Information...2-13 CAUTION...2-13 WARNING...2-13 Electromagnetic Compatibility Information...2-14 3. General Considerations... 3-15 Applications & Capabilities...3-15 Accuracy & Waveform...3-18 Line Voltage Requirements...3-19 Duty Cycle...3-19 Mounting & Installation...3-20 4. Description of Circuits... 4-21 General...4-21 Power Supply...4-21 Output Circuit...4-22 S1 & S2 Output Amplitude...4-22

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5. Explanation of Controls... 5-25 Explanation of Controls. ...5-25 Power...5-25 Setup & Enter/Accept...5-25 Train Rate & Duration...5-26 S1/S2 Timing Parameter Ranges...5-26 Train Rate...5-26 Train Duration...5-26 S1/S2 Rate. ...5-26 S1/S2 Delay. ...5-26 S1/S2 Duration. ...5-26 S1 & S2 Controls...5-27 Function...5-27 S1 & S2 Pulses. ...5-27 Single Pulses...5-28 Output On/Off...5-28 Stimulus Timing Controls...5-28 Output Amplitude...5-29 Sync Out (Synchronous Outputs)...5-29 Sync In (Synchronous Inputs)...5-30 Monitors. ...5-31 S1/S2 LED Monitors. ...5-31 Output On/Off LED Monitors. ...5-31 Output Monitor...5-31 USB Interface...5-31 Duty Cycle Limitations...5-32 6. Computer Control... 6-33 Computer Control...6-33 7. Operation... 7-35 Setup. ...7-35 Duty Cycle Limit...7-35 Choose Stimulus Isolation Units...7-36 Load Setup & Save Setup...7-37 Setting up the S88X Parameters...7-37 Saving the S88X Setup. ...7-37 Loading a Set of S88X Saved Parameters...7-37 Train Parameters Functions...7-38 S1 & S2 Train Delay...7-38 Train Sync Location...7-39 Type of Train Parameters. ...7-39

viii

Table of Contents

Basic Operating Modes. ...7-40 Single Pulses ...7-40 Repetitive Pulses (S1 or S2)...7-41 Single Trains (S1 or S2)...7-41 Repeating Trains (RT) S1 or S2...7-42 S1 Special Modes...7-43 Sync to S1 Delay...7-43 Sync to Train Duration...7-43 S2 Special Modes...7-44 Sync with S1 (SS)...7-44 Post S1 Train (PT)...7-45 Sync Train to S1 (ST)...7-45 Single Arrhythmic (SA) ...7-46 Sync to S2 Delay...7-47 Twin Pulse Mode...7-47 Biphasic Pulse Mode...7-47 Monophasic Pulse Mode...7-48 8. Artifact, Stimulus Isolation & Constant Current... 8-49 Stimulus Artifact...8-49 Sources & Reduction of Stimulus Artifacts...8-50 Stimulus Isolation...8-51 Stimulus Current Monitoring...8-53 9. Troubleshooting & Maintenance... 9-55 General...9-55 Reset Circuitry...9-55 Troubleshooting Tips...9-55 Field Software Upgrade. ...9-56 A. Appendix... A-57 Constant Voltage vs. Constant Current Sources for Pulse Stimulation... A-57 B. Appendix... B-59 S88X Timing Diagrams... B-59

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x

Table of Contents

1

Specifications & Symbols Glossary

Specifications Train Rate (S1 and S2) ������ 1/100 sec to 99 TPS Train Duration �������������� 1 msec to 99 sec Rate (S1 and S2) ������������ 1/100 sec to 1000 PPS Pulse Delay (S1 and S2) ���� 10 µsec to 99 sec Pulse Duration (S1 and S2) � 10 µsec to 99 sec Synchronous Outputs (TTL) � S1, S2, S1 Delay, S2 Delay, Train; Front panel BNC connectors, 50 ohm, 10 µsec pulses, can source/sink 20 mA peak Synchronous Inputs (TTL)��� Train Duration, S1 Delay, S2 Delay; Front panel BNC connectors, 4.75 kohm pullup to 5 volts Stimulus Output������������ 250 mV to 24 volts (monophasic) 250 mV to ±12 VDC (biphasic) Peak Output Current ������� 1 A Output Protection ���������� Yes, current limited Output Impedance ��������� <2 ohms Maximum Power Out ������� 24 W peak AC Power ������������������ 115/230 volts, 50/60 Hz, 100 watts maximum Physical Size ��������������� 19” W x 5.25” H x 12.5” D (48.3 cm x 13.4 cm x 31.8 cm) Weight ��������������������� 10 lbs. (4.5 kg) Regulatory ����������������� Safety: EN 61010-1:2001, UL 61010A-1, CSA C22.2 No. 1010.1-92 EMC: FCC Part 15, Subpart B, Class B, EN 61326:1998 Class B (All specifications subject to change without notice.)

S88X Dual Output Square Pulse Stimulator

1-11

Glossary of Symbols Warnings & Cautions

1-12

Chapter 1 Specifications

2

Introduction

Safety Information CAUTION

Misuse of this product may constitute a safety hazard. Please review the following.

WARNING

The S88X output is not isolated. Do not use on humans. 1.

For use by qualified persons only.

2.

Removal of the S88X Stimulator cover may expose you to lethal voltages and other hazards. Observe labels and caution notices.

3.

Never drop or push objects into the stimulator through cabinet slots, as it is possible to come in contact with hazardous voltages or cause damage.

4.

If the cabinet is damaged, a shock hazard may exist. Unplug the stimulator and have it checked by a qualified person or contact Grass.

5.

Never expose the stimulator to rain or moisture as this can be a potential cause of fire or shock hazard. If the S88X is exposed to moisture, unplug it and have it checked by a qualified person.

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6.

The S88X cabinet has slots for ventilation purposes to prevent component overheating. a. Never cover the slots with cloth or any other material. b. Avoid placing the S88X over radiators or heat registers. c. Never place the stimulator in an enclosure unless proper ventilation is provided and all other related precautions taken.

7.

Operate the S88X only on the power sources as printed on the panel. Damage may result from incorrect voltage.

8.

The voltage/current output of this general purpose stimulator can be lethal or cause tissue damage if not used properly by persons trained in the application intended for this instrument.

9.

Note the output of this general purpose stimulator is referenced to ground, i.e., one terminal of the output is ground. Also all sync inputs and outputs are also referenced to ground. To obtain stimulus potentials isolated from ground choose the appropriate Grass isolation unit.

10.

If this stimulator is to be used with an isolation output, use the proper Grass isolation unit accessory. Contact Grass for application information in writing.

11.

Determination of the safe levels of the stimulation for each application is the responsibility of the investigator in charge.

12.

The investigator in charge is responsible for assuring safe stimulation levels will not be exceeded.

Electromagnetic Compatibility Information The included ferrite EMI suppression cores are required for compliance with EN61326. These should be attached to each output cable by opening the split core, then snapping it together over the cable so that the cable runs through the ferrite core. These should be placed near the output connector on the S88X.

Figure 2-1: Ferrite EMI Suppression Core

2-14

Chapter 2 Introduction

3

General Considerations

Applications & Capabilities The S88X is a dual output general purpose electrical stimulator for nerve and muscle stimulation procedures. Following in the tradition of Grass quality and reliability, the S88X is the next generation of the Grass stimulator line. New Features Include: • Digital controls - precise timing accuracy • Bright display simplifies setup • Independent or synchronous channel operation • Monophasic and biphasic modes • Dual train output • High current output facilitates field stimulation • New companion isolation units • Software replacement The built-in versatility of the S88X Stimulator makes it suitable for unlimited stimulation protocols. The S88X has four parameter control of the two independent outputs. In addition to single, repetitive, twin pulses, biphasic pulses, monophasic pulses, pairs of unlike pulses, trains of pulses, and post train pulses, continuous or trains of pulses are available at one output with continuous or discontinuous operation at the other output. The two outputs can be connected to the same preparation site providing the outputs are isolated from ground using the SIU-C, SIU-V, SIU-BI or the PSIU6X Stimulus Isolation Units. The S88X also includes the capability to introduce an arrhythmic pulse within a cycle of pulses, especially useful for research by cardiophysiologists studying atrial and ventricular fibrillation.

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The S88X makes use of current technology in it’s design. A DAC (Digital Analog Converter) is used to generate the output pulses, and a FPGA (Field Programmable Gate Array) to reduce the size. Software can be updated via the USB interface connector located on the rear chassis. See Chapter 7 Explanation of Controls for instructions. The S88X is a general purpose stimulator and not intended for human stimulation procedures. The S88X is not designed for electroshock therapy, for the creation of localized brain lesions or for electroanesthesia. The design includes Fail-Safe shutdown circuitry which limits the output current and prevents component damage in response to overload or accidental short circuiting of either output. The S88X can provide three types of pulses; monophasic, biphasic, and twin. See Figure 3-1a, b, and c. As shown in Figure 3-1b, the biphasic mode provides equal and opposite amplitude phases. This mode is especially suited to applications where relatively long-term stimulation of implanted electrodes is anticipated and minimization of ion transfer from metal electrodes to tissue is desired.

All modes and timing parameters are displayed on the Vacuum Fluorescent Display. In general, the following steps are used to set parameters. 1. 2. 3.

4.

Figure 3-1a: Monophasic Waveform

Figure 3-1b: True Biphasic Waveform

Figure 3-1c: TWin Waveform

Select S1 or S2 FUNCTION, then use the TIMING thumbwheel dial to select the function. Select appropriate PULSES and use the TIMING thumbwheel dial to select the pulse type. Select the TIMING RATE, DELAY, and DURATION values and the TRAIN RATE and DURATION values using the TIMING left and right arrow keys and the thumbwheel dial. Adjust the desired output voltage using the OUTPUT AMPLITUDE left and right arrow keys and the thumbwheel dial.

Note: To increase or decrease the rate, delay, duration or output amplitude use the left and right arrow touch-pad controls to select the digit to be changed. The number that is flashing is the number that is selected. Then use the thumbwheel control to increase or decrease that number.

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Chapter 3 Applications & Capabilities

The display is divided vertically. The left side displays the selected channel, S1 or S2, function, type of pulses; monophasic, biphasic, or twin, and the output amplitude (volts). The right side of the display is used for displaying the Delay, Duration, Rate, Train Rate and Train Duration. The graphical symbols accompanying the timing values indicate how the values apply to the waveforms. The right side of the display is also used for any error messages. STIMULATOR #1 FUNCTION = RP PULSES = MO VOUT = 010.00 V

00.00005 S

00.00100 S 0001.00 PPS

N.A.

N.A.

Figure 3-2: Vacuum Florescent Display

Several stimulus isolation units are available for use with the S88X: Model SIU-V Isolated constant voltage Model SIU-C Isolated constant current Model SIU-BI Isolated biphasic constant current Model PSIU6X Isolated battery-operated constant current Selection of the isolation unit is made in the SETUP screen. (SETUP > CHOOSE STIMULUS ISOLATION UNITS) Non-isolated stimuli can be delivered from the S88X directly. To facilitate connecting the S1 and S2 outputs in this mode, two special cables, CAB-21891 are provided with orders that do not include stimulus isolation units.

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Accuracy & Waveform

150 Volts

All timing parameters are crystal controlled and are accurate to within ±0.00005%. This feature provides repeatability for the most demanding applications. Both the rise and fall times of the S88X output pulses are approximately 4 microseconds. Calibration of the duration is based on the average width of the pulse. Figure 3-3 illustrates the pulse waveform at a duration of 10 microseconds.

10 sec

Figure 3-3: Pulse Waveform

Because of this high accuracy, it is seldom necessary to monitor the stimulus. However, when complex pulse patterns are produced and until all basic modes of operation of the S88X are understood clearly, monitoring the output with an oscilloscope is advised. Figure 3-4 shows typical pulse waveforms obtainable with the S88X.

S1

S2

S1

S2

S1

S2

S1

S1 Continuous Stimuli

S1

Single Stimulus

S1 Pairs of Stimuli

Trains of Stimuli

S2

S1

S2

S1

S1

S2

S2 S1 S2 Pre-train Stimulus followed by Delayed Train

S1 S2 Same Train Duration and Rate - Different Number of Pulses in each Train

S1 S2 Same Train Rate - Different Train Duration and Pulses in each Train

Trains with Post Train Stimulus

S1 S2 Trains S1 - Continuous S2

S1 S2 Trains with Mid Train Stimulus

Figure 3-4: Typical Stimulus Waveforms

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Chapter 3 Applications & Capabilities

Line Voltage Requirements The S88X has an IEC320 Power inlet for a standard 3-wire AC cable. The unit accepts 115 to 230 volts, 50/60 Hz. The maximum power is 100 watts. The S88X power inlet accepts a standard 3-wire AC Power cord. The input is 115-220 volts, 50/60 Hz and 100 watts. Fusing is in the S88X power supply.

Duty Cycle Duty cycle is defined as the ratio of the time that the stimulus is on to the total period or interval. Since the time from the start of one pulse to the start of the next pulse in seconds is the reciprocal of the frequency or PPS (T=1/F), the DELAY and DURATION controls should not be set greater than T=1/2F which is equivalent to 50% duty cycle. 100% duty cycle occurs when a circuit is on continuously, as with DC. Note: If TWIN or BIPHASIC PULSES are selected, the duty cycle is calculated as twice the pulse time divided by the period multiplied by 100.

The S88X duty cycle limit can be set in the SETUP function. The default value is set to 50%. Values from 0 to 99% are selectable. The S88X display will flash and limit the value when the selected duty cycle is exceeded while making a selection with the OUTPUT ON/OFF on. During setup, with the OUTPUT ON/OFF in the off position, a duty cycle message will display if the duty cycle is exceeded. In these messages, the DCWL value is a percentage and is the Duty Cycle Warning Level. When the output is initially turned on, all parameters will be checked against the duty cycle limit. If the limit is exceeded, a message will be displayed. The output will not be turned on until the output is below the duty cycle limit. Example #1: 50% duty cycle occurs if there is on-off symmetry, as with a symmetrical square wave, where the on time (or pulse duration) is equal to the off time (or time between pulses) for one cycle. See Figure 3-5. T = 1/F

“on” time

“off” time

Figure 3-5: 50% Duty Cycle

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The 50% duty cycle can never be exceeded if the DELAY and DURATION controls are set for less than 500 µs. If the DELAY circuit is not being used, always set the DELAY controls for less than 500 µs. Most triggered circuits, such as those in the S88X, cannot be driven satisfactorily over 90% of their duty cycle. Although the stimulator will not be harmed if the duty cycle is exceeded, the stimulator calibration may be affected if operated above a 50% duty cycle. The train duration should not exceed 50% of the TRAIN RATE settings.

Mounting & Installation The S88X is housed in a compact cabinet 9” W x 5.25” H x 12.5” D (48.3 cm x 13.4 cm x 31.8 cm) and can simply be placed on a laboratory table. An optional Model S88XBT adjustable bench-top stand to mount one stimulator is also available. The S88X can also be rackmounted in a standard 19” equipment rack with the optional Model S88XRK rackmount brackets. When rackmounting, be sure to provide adequate spacing around the S88X for ventilation. Do not cover the ventilation holes in the S88X cabinet.

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Chapter 3 Applications & Capabilities

4

Description of Circuits

General To distinguish the various functions of the S88X, color coding has been used. S1 functions S2 functions RATE, DELAY and DURATION SYNC terminals

= Blue = Green = Yellow = Gray

Most switches are membrane touch-pad type offering extreme reliability. Settings are displayed on the front panel, bright, vacuum florescent display.

Power Supply The S88X power supply provides highly regulated DC voltages for circuit operation. No adjustments are required. The following DC regulated voltages are generated: +27 volts DC +12 volts DC +5 volts DC +3.3 volts DC +2.5 volts DC -15 volts DC VREF 2.5 volts DC

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