Ed Ginzel, Author at Innovation Polymers https://innovationpolymers.ca/author/eginzel/ Moulded Polymers for Ultrasonic Applications Mon, 02 Mar 2026 23:50:29 +0000 en-US hourly 1 https://wordpress.org/?v=6.8.5 https://innovationpolymers.ca/wp-content/uploads/2023/07/cropped-ip-Widget-32x32.png Ed Ginzel, Author at Innovation Polymers https://innovationpolymers.ca/author/eginzel/ 32 32 Frequency Considerations for Aqualink™ 100 https://innovationpolymers.ca/frequency-considerations-for-aqualink-100/ Thu, 16 Jan 2025 00:14:32 +0000 https://innovationpolymers.ca/?p=953 Prepared by: Ed Ginzel

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High frequency ultrasonic wheel applications may have become easier based on the Aqualink 100 material.

A series of waveforms were captured from a 6mm diameter 15MHz Alpha2 Aerotech probe. This probe is a typical delay line probe with a Rexolite delay line approximately 9.5mm long.
6mm diameter 15MHz Alpha2 Aerotech probe

With the probe coupled to the delay line, the signal from the Rexolite/air interface was captured using a PCPR100 pulser-receiver tuned to 15MHz and using a 1 cycle bipolar pulse at 225V (i.e. 450Vpp). The waveform and FFT are seen here for the Rexolite condition.

PCPR100 pulser-receiver tuned to 15MHz and using a 1 cycle bipolar pulse at 225V

A spectral analysis of the FFT indicates that for the -6dB drop, the centre frequency downshifts to 11.7MHz in Rexolite.

spectral analysis of the FFT
Signal analysis results

The probe was then removed from the Rexolite delay line and placed in a small water column approximately 14mm with a tungsten carbide plate used as a target to ensure a high acoustic impedance. The waveform and FFT were collected and displayed here.

waveform analysis
FFT analysis

A spectral analysis of the FFT indicates that for the -6dB drop, the centre frequency downshifts to 12.8MHz in water. There is no discernable dispersion in water so it may be assumed that the internal damping (back loading) is limiting the natural frequency of this probe. This would imply that the Rexolite is causing a 1MHz downshift in frequency content.

Signal analysis results

With the probe removed from the Rexolite delay line it was placed on a 5.5mm thick sample of Aqualink100 and coupled with a medical gel couplant and the tungsten carbide plate coupled to the opposite surface of the Aqualink100. The waveform and FFT were collected and displayed here.

spectral analysis
FFT analysis

A spectral analysis of the FFT indicates that for the -6dB drop, the centre frequency downshifts to 8.2MHz in Aqualink100 compared to water. This is a relatively large “centre frequency” downshift; however, the bandwidth increased from 29% in water to 114% in Aqualink. There is some variability in signal frequency content with regards to the method used (i.e. manually holding the probe on the sample). The Spectral analysis shows a Peak frequency of just 7.03MHz, yet the above FFT indicates a peak had occurred at a point nearer to 11MHz.

Signal Analysis Resullts

A review of Aqualink properties from the MAPAS software analysis shows that at 5MHz there was essentially no downshift in centre frequency.

MAPAS software analysis

With this in mind, a pulse-echo signal was obtained using the 5.5mm thick sample used with the 15MHz probe and it was placed in direct contact on an immersion probe with a 10MHz nominal frequency and 12.5mm diameter.

The probe was driven at 225V negative bipolar and tuned to exactly 10MHz. It was noted that by adjusting the number of cycles from 1 to 4, the centre frequency moved upward. With 4 cycles, the resulting frequency peaks at 8.98MHz.

Aqualink is a tough durable polymer compared to Aqualene. A relatively thin wall tyre may offer an alternative to allow Aqualink 100 to be used for high-frequency (10-12MHz) ultrasonic wheel applications. Consider too that even Rexolite noticeably downshifts high-frequency pulse content.

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