User Instructions & Part list
  for DNIC stimulator pressure controller

User Instructions


Using the stimulator

The stimulator should be powered from a source of clean, preferably dry, compressed air with a pressure between 80 and 125 psi.  The air source should be filtered to remove particulates larger than 5 microns.

The manual safety valve should be set with its toggle lever pointing away from the pressure gage before connecting the stimulator to a source of compressed air.  This vents the subject contactor assembly (syringe) to the atmosphere.

If you are using the computer controlled version of the stimulator, which has an electronic regulator, you must be sure that power is reaching the regulator (power LED is on) before applying compressed air.  Shut off compressed air before removing power from the regulator.

If you are using the manual controlled version turn the adjustment knob on the manual pressure regulator until the pressure gage reads about 2 psi.  The subject can than then insert his/her thumb into the contactor assembly with the thumbnail positioned below the syringe.  Then move the manual safety toggle lever toward the gage.  This will pressurize the syringe and push the contactor down onto the thumbnail.  At this minimal pressure it will be easy for the subject to adjust the position of the thumb.  The edge of the silicone rubber cushion should be close to, but not on, the cuticle.

At the end of the session reduce the pressure to below 5 psi, then flip the manual safety toggle away from the gage to vent the syringe to the atmosphere again.

The source of compressed air should be turned off after the session is completed.

The subject contactor assembly can be wiped with common disinfectants if it is desired to clean it between sessions.

Total force on the thumb:

The head of the syringe plunger against which the compressed air acts has a surface area of about 0.264 square inches. To compute the total downward force on the thumb (in pounds) multiply the pressure gage reading by 0.264.

Safety considerations:

If the regulator fails there are two automatic safety relief valves that will limit the pressure to 50 psi. To avoid blowing the safety valves during experiments you should not ask for pressures higher than about 45 psi.

Pressure can be released instantly at any time by flipping the manual safety valve toggle. This can be done either by the investigator or the subject.

Plastic pressure hoses and the clamps that hold them in place should be inspected frequently for signs of wear or damage.

The subject contactor assembly is made entirely of nonconductive plastic. There are no electrical hazards associated with this stimulator.

Use in an MRI environment: The subject contactor assembly is MRI safe. The pressure control assembly is notMRI safe and must be positioned sufficiently far from the MRI magnet.  The plastic hose connecting the control assembly to the contactor assembly can be lengthened as needed, although the extra "dead space" may have some small effect on performance.


The manual pressure regulator has a pin-hole bleed vent located in the middle of a red colored screw on the side of the unit. If regulation becomes unstable the vent may need to be cleaned. Remove the screw and make sure the screen and the orifice in the tip of the screw are not blocked by foreign matter.

Part list:

Part location photo.


Smiths Medical

Smiths Medical #4905. "Pulsator" L.O.R. (Loss of Resistance) syringe. 7ml, Luer Lock. This syringe serves as the pneumatic piston of the thumb stimulator. It's plunger is specially designed for low friction movement. Do not use ordinary syringes!


Parts for Main Air Supply

MSC  #01780170.  Norgren miniature compressed air filter, 5 micron element, 1/4-inch NPT fittings. Use to filter the source of compressed air. Place as close to the regulator as practical.($22.12 each July 2007)

MSC #01780873. Norgren replacement filter elements, 5 micron($3.33 each July 2007)

MSC #05642020. Pressure gage, 160 psi, accuracy +/- 0.5% full scale, 1/4-inch NPT. Manufactured by McDaniel Controls, Inc.($63.15 each July 2007)

Part for Manual Unit

MSC #74700394 Ingersoll-Rand "ARO" manual precision pressure regulator. Low-flow type, range 2 to 60 psi, 1/4-inch NPT fittings. Maintains set pressure to within 0.1 %. Input pressure should be at least 20 psi above output pressure. Requires 5 micron filter. ( $134.79 each July 2007)

Parts for Manual and Voltage Controlled Units

MSC #09881392 1/4F X F FLUOR BRASS BALL VALVES 2-WAY. Cutoff valve for the main compressed air line($35.75 each July 2007).

MSC #61233060 Toggle valve, (3-way "exhausting" type). Toggles the syringe between the current regulated pressure and the open atmosphere. Can be used to instantly reduce the pressure to zero if a problem occurs($9.31 each July 2007).

MSC #08061640. Primary automatic safety relief valve, fixed setting, 50 psi. This device is ASME approved ($11.80 each July 2007).

MSC #78705449. Norgren adjustable pressure relief valve 1/4-inch NPT fittings. Used as a secondary safety valve. Set so that air just begins slowly venting at a gage reading around 45 psi. Volume of air released will increase steadily if pressure climbs above this point($17.15 each July 2007)

MSC #05642004. Pressure gage, 60 psi, accuracy +/- 0.5% full scale, 1/4-inch NPT. Manufactured by McDaniel Controls, Inc. ($63.15 each July 2007)

MSC #06430284. Aluminum manifold, 2 ports of 3/8-inch, 6 ports of 1/4-inch. Has more ports than needed to allow for future modifications($23.46 each July 2007).

MSC #75048306. Sintered bronze muffler. Attach to main exhaust port of electronically controlled pressure regulator to reduce noise(Not used with manual regulator.) Has 1/8-inch pipe threads.($2.38 each July 2007)

MSC #84278910. Silicone rubber sheet with adhesive backing, 1/16-inch thickness, hardness 50 durometer. Cut to size and place on end of syringe plunger as a cushion for the thumbnail. This material is FDA approved. Comes in other thicknesses and degrees of hardness. Might be worth trying the 1/8-inch thick sheets (#84278944). The adhesive applied at the factory isn't very good. It may be better to remove it and use sticky "electrode washers" for attachment to the syringe plunger($13.20 each July 2007)

MSC #60058096.3/4-inch arch punch. Useful for cutting silicone rubber sheeting into uniform round disks($13.09 each July 2007)

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In Vivo Metric

In Vivo Metric   #E401.  Electrode washers with double sided adhesive.

Small Parts #PUT-03 Ether-based polyurethane tubing. 3/16-inch I.D.

Small Parts #PUT-02 Ether-based polyurethane tubing. 1/8-inch I.D.

Small Parts #LCN-F125 Female Luer to 1/8-inch hose barb adapter. Connects syringe to hose.

Small Parts #TFN-BAM125/1032 Male 10-32 thread to 1/8-inch hose barb adapter. Connects toggle valve to hose.

Small Parts #QCB-03 Brass quick-disconnects with barbs for 3/16-inch I.D. tubing.

Small Parts #QCB-02 Brass quick-disconnects with barbs for 1/8-inch I.D. tubing (x2).
Small Parts #CHN-04 Plastic "snapper" clamps for 1/4-inch O.D. tubing.

Small Parts #CHN-05 Plastic "snapper" clamps for 5/16-inch O.D. tubing.

Small Parts #CHX-04 Stainless worm gear clamps for tubing. May work better than "snapper" clamps with some types of hose barbs.

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Proportion Air

Proportion-Air web site.

Unfortunately the links to "Proportion-Air" documents in the following paragraph are no longer valid, which probably means that the original pressure regulator is no longer available from the company.

Proportion-Air #BB2MFEE060 / PSR-2 (Brochure pdf & Data Sheet pdf  ). Electronically controlled pressure regulator with volume booster.  This device can optionally replace the manual pressure regulator if it is desired to control the thumb stimulator via computer. The input signal is 0 to 10 volts DC for a requested output pressure of 0 to 60 psi. The unit provides a pressure monitor output signal which is also 0 to 10 volts.  These devices are custom made and require a lead time of several weeks.  Requires a 15 volt DC power supply (#PS4515) and a cable with a five pin connector (#H6512). Installation instructions. ($1,061.00 May 2005 quote)

Aquatic Eco-systems

Aquatic Eco-systems #C401010. Schedule 40 PVC "Tee", 1-inch, clear, slip. This clear pipe fitting forms the main body of the subject contactor assembly. (A 1-inch PVC cap and a short length of 1-inch pipe are also needed but these can be made of the regular opaque PVC that is found in local hardware stores.)

Newark Electronics

Newark Electronics #52F6719. Brad Harrison 5-pin female connector, type 1A5000-34. This attaches to the top of the Proportion-Air regulator if you want to make a replacement for the heavy yellow cord that is standard on the voltage-controlled regulators. ($28.20 On Line Catalog July 2007 )


Assorted brass pipe fittings are needed for assembly. Can be purchased from MSC or local hardware store.

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  & Michael G Young

Original May 5, 2005
Last update January 15, 2009