Ultrasound exposure in a workplace and a potential way to improve its measurement methodology

Prolonged exposure to airborne ultrasound in a workplace can have a detrimental influence on worker's wellbeing. Given the large number of industrial machines producing ultrasound, it is of vital importance, and can also be regulated by law, to monitor one's ultrasound exposure during a normal workday as part of risk assessment in a workplace. However, currently utilized devices exhibit limitations in regard to their operational frequency, as well as their portability (wearability). These limitations have been recognized by the Physikalisch-Technische Bundesanstalt (PTB) and the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA of DGUV). In this paper, specific requirements, based on national and international standards, for a portable ultrasound exposimeter are discussed. Key elements of such a device are also identified and selected for practical investigation. Two analog to digital converters (ADS127L01 and ADS1672), with the sampling rate covering the ultrasound spectrum up to at least 100 kHz, were tested. They were in turn connected to a readout electronics centered around 180 MHz ARM-based Cortex-M4 microcontroller. Results obtained during tests with purely electrical signals suggest a good potential of these devices to be able to reliably record ultrasonic signals. A new approach to personal ultrasound instrumentation, based on recent developments in the field of microelectronics, is then discussed. Future directions of this work are subsequently indicated, together with its applicability to other research fields.