SpecialsNeedle Tip Pressure Transducers

Robust metal sensing diaphragms within a polished surgical steel needle

Excellent frequency response and resolution and compatible with a wide range of amplifiers and monitors.

Our Needle Tipped Pressure Transducers / probes fall into two main categories:

  • Low pressure (LP) for standard physiological pressure ranges of up to 300mmHg
  • High Pressure (HP) for pressures up to 3MPa

Both types have a sensor mounted on the side of the needle close to the tip.

Standard design

Our standard Pressure Needle Transducers are manufactured using 4F diameter material and are available in needle lengths of 95mm or 145mm.

The tip can be supplied domed, pointed or sharpened as standard.

The centre of the sensor is positioned 5mm from the tip.

The standard device has a 500mm long flexible silicone rubber lead terminated in a lightweight 6-pin Lemo connector. The sensor is mounted in a stainless steel needle.

Non-standard designs

We are also pleased to supply non-standard needles (these may cost a little more and/or take a little longer to supply depending upon the design required):

  • Lengths from 20mm upwards
  • 3F diameter (NB these are very fragile and the length should be as short as possible)
  • Other French sizes (3F, 5F or 6F low pressure only)
  • Position of sensor to tip (5mm minimum)
  • Cable length
  • Tip shape
  • Intermediate pressure ranges
  • Needle material specification

Low pressure needles (CTN/3F to CTN/6F)

The standard pressure range of LP needles is zero up to 300mmHg. The sensitivity of LP needles are in common with other Gaeltec physiological pressure transducers. i.e. 5µV/V/mmHg. The sensitivity of 3F needles is 2.5µV/V/mmHg.

These devices can be used for invasive pressure measurement of, for example, Compartment Pressure and similar measurements and for experimental in vitro situations.

As the sensor is an analogue device it has an infinite resolution. Pressures in increments of 0.5mmHg may be recorded (providing the amplifier etc. used has the necessary accuracy and resolution).

For medical use they MUST be used with a medically approved patient isolated monitor or amplifier approved for use in the country concerned.

High pressure needles (CTN/4F-HP)

The standard pressure range of HP needles is from zero up to 3MPa and the sensitivity is approximately 0.75µV/V/kPa.

As the sensor is an analogue device it has an infinite resolution. Pressures in increments of 10kPA may be recorded (providing the amplifier etc. used has the necessary accuracy and resolution).

The HP Needles are most often used for in vitro pressure distribution measurements on spinal disc models and/or cadavers. For this application the preferred specification is a 4F needle, 145 mm long and with a domed tip. The distance from the tip to the middle of the sensor is 5mm. The sensor is mounted in a 3.5mm long "window."

For medical use they MUST be used with a medically approved patient isolated monitor or amplifier approved for use in the country concerned.

Monitors, Amplifiers and Data Acquisition (DAQ)

All needles are suitable for use with medically approved isolated amplifiers such as the IBP channel of most patient monitors. If the Monitor cannot supply a 1V excitation supply, we offer our S13 Interface Unit. If an Isolated Patient Monitor is not available, we offer our S7d-Mk.2 Isolated Interface Unit (for low pressure needles only).

If patient isolation is not required, such as research with animals, cadavers or models then we can offer our Gaeltec Bridge Amplifier (GBA) which is available with 1, 2, 3 or 4 channels and may be used for both high and low pressure needles.

We also offer a low cost Data Acquisition System (GAS-4) which may be connected between the bridge amplifier and your computer. Free PC software is available.

Scientific Papers and Presentations using Needle Pressure Transducers

  • Internal Intervertebral Disc mechanics as revealed by Stress Profilometry. D S McNally, PhD and M A Adams, PhD: Click here to read this paper.
  • Development and validation of a new transducer for intradiscal pressure measurement. D S McNally, PhD, M A Adams, PhD and A E Goodship: Click here to read this paper.

Suggested uses

  • Intradiscal pressure
  • Intervertebral pressure
  • Compartment pressure
  • Lymph Node pressure
  • Lumber pressure of facet joint
  • Thoracic intervertebral disc disorder (IVD)/Lumber Spondylosis
  • Human lumbar intervertebral disc
  • Intradiscal pressures of intervertebral discs

Technical details:

Sensor:

Metal diaphragm with directly deposited resistive strain gauges

Excitation:

5V AC r.m.s. maximum or 1V DC maximum

Bridge resistance:

1kΩ nominal

Sensitivity:

LP = 5µV/V/mmHg; LP 3F sizes = 2.5µV/V/mmHg. HP approx. 0.75µv/V/kPa

Linear pressure range:

LP = Standard pressure range 0 to 300mmHg
HP = Standard pressure range 0 to 3MPa (approximately 435 psi or 30 bar)

Compensated temperature range:

15 - 40°C

Temperature coefficient of zero:

< 0.05%FS/C°

Temperature coefficient of sensitivity:

< 0.2%/C°

Linearity and hysteresis error:

< ±1%FS BSL

Overpressure:

LP = 1000mmHg; HP = 3.5 MPa


General

Needle:

Standard material is 304 Stainless steel (316 may also be supplied, non standard)

Cable:

Reinforced flexible with silicone rubber jacket

Connector:

6 pin Lemo 2 series

Extension lead:

Type ELF-1 NB The lead has a 6 pin Lemo 2 series at one end and bare wires at the other. Connectors suitable for your amplifier/monitor may be fitted at extra cost.

Useful information

See our information section for anything from "What a Gaeltec Pressure Transducer is" to "Can I have a Transducer with Double Lumen, Twin Bore, Pig Tail with an Extended Tip?" Click here

Making a Gaeltec Catheter

Gaeltec product gallery