In this work, we study the effect of transistor downscaling in a wireless communication circuit for Body Dust application. The system requires a chip lateral size smaller than 10 mu m miming the typical size of a red blood cell and so, supporting free circulation in human tissues. Moreover, an ultra-low-power architecture is needed since the system is battery-less and wirelessly powered via acoustic power transfer. The aim of this paper is to present a data communication system for Body Dust systems, which works from the multiplexed sensor read-out front-end to the transmitter back-end taking account diagnostic information on different metabolite concentrations in human body. This work shows that scaling the architecture from a 0.18-mu m to 28-nm CMOS processes, it is possible to improve both size and power consumption. The improvement is about 40 times in size (2000 mu m(2) down to 50 mu m2) and two order of magnitude in average power consumption (10 mu W to cents of nW).