Keynote Speakers

Dong-Sing Wuu
Fellows of SPIE, OSA, IOP
Department of Materials Science and Engineering,
National Chung Hsing University, Taichung 40227, Taiwan

Title of Keynote Speech
Passive-Matrix Micro-LED Displays with Advanced Process Integration

Abstract of Keynote Speech
The light-emitting diode (LED) is a self-emissive device with high response time, brightness, and color saturation properties. It possesses the high thermal and humid stability, which is suitable as a next generation displays. However, for achieving the high resolution, the pixel size should be downsized into a few micron scale. In this study, the pixel size of micro-LED was investigated from 100×100 μm2 to a 10×10 μm2, where a laser direct writing technique was employed. The direct writing technique does not need the photomask and can improve the exposure accuracy with minimized image distortion. However, for the smaller pixel sizes, the plasma damage from the dry-etched sidewall of pixel became more evident and would degrade the light extraction efficiency. Therefore, the surface passivation processes e.g. spin coating, PECVD, ALD have plays an important role in determining the leakage current levels. As a result, the external quantum efficiency of 10×10 μm2 pixel size can achieve 18.81% under a current density of 136.8 A/cm2. The brightness of blue micro-LED display with a pixel size of 20 x 20 μm2 was 516 cd/m2 at 3 V under the full lighting state. Using the advanced process integration, the performance of the blue, green and red passive-matrix micro-LED displays with 150-250 pixel-per-inch resolution will be described. Future applications of these small-size micro-LED displays will also be discussed.

Dr. Srinath Rajagopal
Principal Research Scientist
National Physical Laboratory, United Kingdom

Title of Keynote Speech
Metrology in Medical Ultrasound

Abstract of Keynote Speech
The earliest application of ultrasound in medicine dates back to 1940s when its therapeutic effects were demonstrated by successfully destroying brain tissue in animals. It was nearly after a decade later the first diagnostic capability of ultrasound in the detection of breast carcinoma was reported. The ultrasound-induced damage to tissue in therapy did not go unnoticed as the diagnostic use of ultrasound continued to rise in the 1950s and 1960s especially in monitoring of foetal development. In 1980s US Food and Drug Administration initiated the regulation of diagnostic ultrasound equipment. The regulation placed restriction on the ultrasound exposure level, which has been adopted by the manufacturers globally.

The ultrasound exposure levels are quantified by the measurement of the two key quantities, pressure and power. These two quantities represent potential mechanical and thermal damage to tissue under certain excitation conditions. Manufacturers are required to perform measurements under a number of different operational conditions to demonstrate equipment safety. The devices used to make measurements of pressure and power must be traceable to International System of Units (SI) via their calibration at a National Measurement Institute (NMI) for example, National Physical Laboratory, U.K or National Measurement Laboratory, Taiwan.

Hydrophones are used to make the measurement of the dynamic pressure of ultrasound and whereas Radiation Force Balance (RFB) is to measure the ultrasound power. The highest measurement standards applied in the determination of a physical quantity is known as a primary standard. The primary standards for ultrasound pressure and power along with systematic effects, which affect the measurement quality, traceability and dissemination will be described. The emerging technologies in medical ultrasound poses new challenges to measurement and recent efforts to address these challenges will also be covered.