PhD project by Rune Sixten Grass

Name: Rune Sixten Grass
Project Title: Micromachined Integrated 2D Transducers for Super Resolution Ultrasound Imaging
Group: MEMS Applied Sensors
Supervisors: Erik Vilain Thomsen and Jørgen Arendt Jensen

Project Description: 
The aim of this project is to fabricate CMUT probes which are suitable for making large 2D arrays used for 3D ultrasound super resolution imaging (SRI). Modern medical ultrasound imaging is made using multi­element piezoelectric transducers. Often the arrays are one dimensional and consist of 192 elements with a spacing between elements of one or a half wavelength (λ/2). The frequencies used is in ultrasound is typically between 3 to 15 MHz making the wavelength around 0.5 to 0.1 mm. This makes individual elements difficult to manufacture using piezoelectric crystals with conventional methods. Furthermore, progressing from 1D to 2D arrays introduces challenges with the increase in interconnections needed to access individual elements, with e.g. a 64 x 64 array needing 4096 connections. Some of these challenges can be alleviated by using standard semiconductor manufacturing techniques to make capacitive ultrasonic micromachined transducer (CMUT) based 2D arrays. These CMUT elements can also be made smaller than their piezoelectric counterparts. If the 2D arrays are addressed as rows and columns, by e.g. using only 192+192 interconnections instead of 192 x 192, they can readily be made larger to achieve better resolution. These arrays also have the potential of SRI by detecting and tracking micro bubbles.


Probes made with 2D transducer arrays will in this project specifically be used for the screening of kidney and liver cancer. This will be done performing 3D volumetric scans of the organ and its blood flow, both before, during and after treatment. It has the potential of replacing the existing piezo-based transducers and improving the microvasculature image quality using SRI at hospitals for diagnostic purposes.  Ultrasound has the potential of replacing or becoming a complementary technique to existing scanning methods such as MRI and X-ray.


Rune Sixten Grass
DTU Health Tech
+45 42 28 00 68


Erik Vilain Thomsen
Head of Division, Professor
DTU Health Tech
+45 45 25 57 66


Jørgen Arendt Jensen
Head of Section, Professor, Ph.D., Dr.Techn.
DTU Health Tech
+45 45 25 39 24