Ultrasonic arrays for ultrahigh resolution real time biomedical imaging

Lead Research Organisation: Institute of Cancer Research
Department Name: Division of Radiotherapy and Imaging

Abstract

The project involves collaborative, multidisciplinary work combining materials research, device design, and medically-oriented testing to create ultrasonic arrays capable of ultrahigh resolution biomedical imaging in real time. Real-time ultrasonic imaging is a safe, inexpensive and convenient technique which accounts for approximately 20% of all hospital imaging examinations. However, spatial resolution is ultimately limited by maximum frequency and existing ultrahigh resolution systems are based on mechanically-scanned single-element transducers. Such systems demonstrate the need for increased resolution but at the same time limit progress because they cannot be used in real time. For this, ultrasonic arrays are needed which can operate at frequencies higher than the present maximum of ~30 MHz. However, it has so far been impossible to produce such arrays.Piezocomposite materials, comprising ceramic pillars in a polymer matrix, are now state-of-the-art in commercial ultrasonic imaging systems, with higher electromechanical coupling, better acoustic impedance matching to biological tissue, and better electrical properties than piezoceramics alone, leading in turn to wider intrinsic bandwidth and higher sensitivity. In addition, reduced lateral coupling means that multi-element arrays can be defined from monolithic piezocomposite plates. However, difficulties manufacturing material with micron-scale dimensions has blocked adoption in high frequency ultrasonic transducers and arrays. In the research programme being proposed, ultrasonic arrays will be created to operate for the first time at frequencies potentially as high as 100 MHz, suitable for ultrahigh resolution imaging in real time. The key to this advance will be the ultrafine scale piezocomposites we will produce with optimised net shape ceramic processing technology, in combination with state-of-the-art composite design. This will be a major step forward in enabling real time biomedical ultrasonic imaging at presently impossible frequencies, ultimately allowing new understanding and better diagnosis of a range of medical conditions in areas such as dermatology, ophthalmology, small parts cancers, dentistry, and the cardiovascular system, sometimes in intralumenal configurations.
 
Description Developed and evaluated on phantoms and biological specimens the technology for manufacture of ultrasound arrays with pitch equivalent to 100 MHz operation using piezoelectric composites that can be manufactured using vacuum molding methods that are efficient and do not require cutting to define the elements. A method was also developed for the design of the pillars (subunits of the composite) to be of random shape with controlled parameters for the randomness, which greatly reduced unwanted modes of vibration, which should generate a purer broadband high frequency signal.
Exploitation Route These transducer manufacturing methods are expected to improve very high resolution (microscopy) imaging in vivo. They are being taken forward at the University of Dundee and at the University of Birmingham.
Sectors Healthcare

URL http://www.icr.ac.uk/our-research/research-divisions/radiotherapy-and-imaging/ultrasound-and-optical-imaging/research-projects/high-frequency-transducers-and-arrays
 
Description Resulted in a patent and invited short course at the IEEE International Ultrasonics Symposium on high frequency transducer manufacturing, characterisation and application. Applied Functional Materials Ltd., Birmingham, have taken over the patent for their future manufacturing portfolio. The University of Dundee have several follow-on grants using the technology developed. A further grant application is planned to build a demonstration system for skin cancer diagnosis.
First Year Of Impact 2009
Sector Healthcare
Impact Types Societal

 
Description Multimodality techniques for cancer diagnosis and therapy (EPSRC Platform Grant)
Amount £1,656,697 (GBP)
Funding ID EP/H046526/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 10/2010 
End 09/2015
 
Title Ultasound Transducer Array 
Description A method for vacuum molding manufacturing what is known as a piezoelectric composite material using a randomized pillar structure with controlled parameters of the randomization which greatly reduces unwanted modes of vibration rendering a purer ultrasound emitted signal with wide bandwidth and good matching to tissue. 
IP Reference GB0916427.8 
Protection Patent granted
Year Protection Granted 2009
Licensed Yes
Impact Patent has since been transferred to Applied Functional Materials Ltd., Birmingham