Specific absorption rate and Histopathology evaluation for mobile phone application

Abstract

This report describes the development of Asian head and hand model using computeraided design (CAD) software and the analysis of specific absorption rate (SAR) at 900 MHz to 1800 MHz with various hand positions. The motivation for this work has been inspired by the lack of research contributions on the effects of SAR towards Asian users since most work is done using European-sized model. To further contribute for the Asian database, Asian-sized hand models are designed, simulated with a planar inverted-F antenna (PIFA) and investigated for the distribution of SAR with the inclusion of the hand model. The radiation effect at 1800 MHz is tested on Sprague- Dawley rats using histopathology approach. The Asian hand model design development begins with simple geometrical model with human tissue properties posed at two common talk-mode positions together with a Specific Anthropomorphic Mannequin (SAM) head model for comparative study and further evolved into a semi-realistic hand model based on a conducted survey. The female Asian hand was chosen after collecting data of the size of typical Asian hand for both male and female ranging from age 19 to 25 years old. The mean size shows that the male hand is similar to the standard SAM hand model commonly used for SAR investigation whereas the female hand is found smaller than that. The SAR investigation is carried on with the average size of female hand model in Computer Simulation Technology (CST) Studio Suite using a candy-bar and clamshell type mobile phone with PIFA radiating at both frequencies in the vicinity of Asian-sized head model. The result have shown that the hand model with layers of common tissues in human hand – skin, bone, muscle and tendon, gave a high value of SAR at 1800 MHz with the spreading pattern smaller but deeper into the ear and cheek part. The various hand models has help to provide a better understanding in hand grip styles that may reduce absorption while in talk-mode. This research continues on animal testing of 100 Sprague-Dawley rats aged 2 to 3 months old exposed whole body to 1800 MHz signal generated by a Standard Gain Horn Antenna for one month and two months duration. The samples taken from the rats are the brain, the skin, the muscle with tendon from the hand of the rat. The samples is sliced in six micron thickness and put under microscope to observe any cell changes. Significant changes in skin samples are obtained, with some patchy appearance found in brain that needed more analysis. As a conclusion, this work offers simple alternative for developing suitable hand model according to the target group of investigation, in this case for Asian database. Compared to the standard hand model, a smaller hand that suits the averaged size of this target group is more reliable and the test on animal has help a lot in understanding biological effects at the level of the cells.