Dielectric spectroscopy for hydration monitoring, from application to portable sensors

Abstract

Due to the earth’s population growth and the increased living age of a person, more and more people could deal with medical problems. Early detection of health related problems in both healthy and people with medical problems, will catch problems early and prevent the need for more costly procedures. One of these medical problems is concerning the hydration level. Dehydration most often occurs for elderly people. To prevent sickness and even death, monitoring of the hydration can play a key factor in prevention. Hydration monitoring can be established by using a designed CMOS permittivity sensor. However, to design a commonly used hydration monitoring device, this CMOS permittivity sensor needs to be designed in such a way that portable sensing could be enabled. To design such a portable hydration sensor from an application sensor, different steps are required. To bring previously developed sensor to enable hydration monitoring, it need to be packaged in such a way that it can sense the medium of interest and be connected to the outside world while sufficiently protected, so that it will not damage during use. Different packaging procedures could be distinguished to accomplish this. The first packaging procedure is regarding the creation of SU8 metallized pillars. The second packaging procedure is for creation of cavities in SU8 and fill these cavities with aluminium particles. Besides the packaging of the sensor chip, validation measurements are required to ensure that a relationship could be detected with the permittivity sensor between the hydration level of the human skin. To enable measurements of the skin permittivity without bulky systems, a PCB layout should be designed.