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J Athl Train. 1996 Oct-Dec; 31(4): 313–317.
PMCID: PMC1318914

The Effectiveness of the Aquaflex Gel Pad in the Transmission of Acoustic Energy



The purpose of this study was to assess the effectiveness of the Aquaflex Gel Pad in the transmission of acoustic energy.

Design and Setting:

This was a comparative study that utilized descriptive statistics for result interpretation. The independent variables included ultrasound intensity, interposed materials, and trials. The dependent variable was peak-to-peak voltage output recorded via an oscilloscope. The study was conducted in a ventilated research laboratory.


Three trials were conducted with six combinations of material interposed between a conducting (1 MHz) and a receiving sound head. The interposed materials were as follows: 1) ultrasound gel, 2) gel plus a gel pad, 3) gel plus a gel pad and pig tissue sample (0.90 cm of subcutaneous fat), 4) gel plus a gel pad and a pig tissue sample (1.8 cm of subcutaneous fat), 5) gel plus thin pig tissue sample, and 6) gel plus thick pig tissue sample. Each interposed material combination was tested at the intensities (W/cm2) as follows: 0.10, 0.25, 0.50, 1.00, 1.50, and 2.50.


The gel pad proved to be an efficient couplant in the delivery of high-frequency acoustic energy. Using ultrasound gel as the base line (100% transmissivity) it was concluded that the gel pad transmitted more acoustic energy at every intensity except at 0.1 W/cm2. The gel pad used with the two thicknesses of subcutaneous fat gave comparable results. Gel used with the two thicknesses of subcutaneous fat yielded results that warrant further investigation.


I believe gel pads are a practical choice for clinical applications of ultrasound over uneven surfaces. The reusable gel pads offer the clinician a convenient and reliable method for delivering ultrasound energy to the patient. I believe it is preferable to use the gel pad with ultrasound gel directly applied to the patient and at the sound head-gel pad interface as opposed to using the traditional water bath immersion method.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Docker MF, Foulkes DJ, Patrick MK. Ultrasound couplants for physiotherapy. Physiotherapy. 1982 Apr;68(4):124–125. [PubMed]
  • Draper DO, Sunderland S. Examination of the law of grotthus-draper: does ultrasound penetrate subcutaneous fat in humans? J Athl Train. 1993 Fall;28(3):246–250. [PMC free article] [PubMed]
  • Forrest G, Rosen K. Ultrasound: effectiveness of treatments given under water. Arch Phys Med Rehabil. 1989 Jan;70(1):28–29. [PubMed]
  • Griffin JE. Transmissiveness of ultrasound through tap water, glycerin, and mineral oil. Phys Ther. 1980 Aug;60(8):1010–1016. [PubMed]
  • LEHMANN JF, MCMILLAN JA, BRUNNER GD, BLUMBERG JB. Comparative study of the efficiency of short-wave, microwave and ultrasonic diathermy in heating the hip joint. Arch Phys Med Rehabil. 1959 Dec;40:510–512. [PubMed]
  • Reid DC, Cummings GE. Efficiency of ultrasound coupling agents. Physiotherapy. 1977 Aug;63(8):255–257. [PubMed]
  • Warren CG, Koblanski JN, Sigelmann RA. Ultrasound coupling media: their relative transmissivity. Arch Phys Med Rehabil. 1976 May;57(5):218–222. [PubMed]

Articles from Journal of Athletic Training are provided here courtesy of National Athletic Trainers Association