For over 15 years, Epoxyset has been formulating and producing many types of high performance adhesives and polymers used in ultrasound technology. Ultrasound technology is not just limited to medical applications such as interior body screening. It is also used in the oil and gas industry for measuring motion and flow, the exploration industry for sensing and measuring, and also consumer electronics such as speakerphone and microphone components.
Basic principle of medical ultrasonic probes (transducer)
The ultrasonic probe consists of a piezoelectric element, backing material, an acoustic matching layer and an acoustic lens. The following describes the components and their functions of the convex type probe as an example:
Epoxyset, as an advanced adhesive manufacturer, applies its proprietary technologies to the probe manufacturing processes, such as formulating and producing backing layer elements and bonding of acoustic matching layers as well as innovative acoustic lens material.
Piezoelectric Element (PZT)
The piezoelectric element (PZT) is the part of the transducer that generates ultrasonic waves. On both sides of the PZT element electrodes are affixed and a voltage is applied. The element generates a sound wave by oscillating due to repeated expansion and contraction. When the element is externally applied with vibration (or an ultrasonic wave) in turn, it generates a voltage.
Function of the backing material
The function of the backing material is to reduce and/or prevent excess vibration of the piezoelectric element. The backing material is located directly behind the PZT element. By reducing excessive vibration will cause the element to generate ultrasonic waves with a shorter pulse length, improving resolution in images. Epoxyset produces a number of backing materials for various transducer manufacturers. Working closely with these companies, Epoxyset utilizes different polymers, additives, fillers, and curing agents to deliver a backing layer suitable for the need of the transducer.
Function of the Matching Material
Ultrasonic waves transmitted from the PZT element are reflected off a target because there is a big difference in acoustic impedance between the piezoelectric element and the object. To avoid this, an intermediate layer is (matching layer) is added between the two so that ultrasonic waves can efficiently enter the object. It is not uncommon to have several different matching layers in a single transducer to gradually decrease impedance between the PZT element and the object. Epoxyset offers acoustic matching layers to have adequate acoustic impedance value using a combination of different resin materials, fillers, and additives. It is important to deliver a product that not only offers the appropriate acoustic properties but also is easily processed and applied.
Function of the acoustic lens
The acoustic lens is the outer layer most people see when they look at an ultrasound transducer. It is usually grey or black or green and looks like a rubber attached to the end of the probe. Ultrasonic waves transmitted from the probe would spread and travel like light. The acoustic lens prevents the ultrasonic waves from spreading and focuses them in the slice direction to improve the resolution.
When the probe emits ultrasonic waves, they would travel like light and spread in all possible directions without a lens. The acoustic lens prevents the ultrasonic waves from spreading and focuses them in the slice direction to improve the resolution. On many probes, the lens material is usually a commercially available silicone adhesive. However, for higher sensitivity probes silicones are not acoustically viable. Epoxyset develops new and innovative lens and window castings for high sensitivity probes using proprietary polyurethane chemistry.