Figure 3.

Wireless performance and lifetime of gastric-residence electronics. A) Average received signal strength indicator (RSSI) of seven devices measured with a smart phone. Inset shows an X-ray image of the integrated electronics at the GRE with three major components. B) The RSSI measured from GRE in a porcine stomach. The distance is measured relative to the abdominal surface of the pig. The in vivo measurements are repeated in three orthogonal directions. Inset shows the stability of RSSI measured at fixed location. C) GRE bilateral wireless communications from the gastric space: the change of temperature measured from GRE delivered to the porcine stomach, demonstrating the ability to perform bilateral wireless Blue-tooth interconnection between the device in the gastric space and a smart phone. D) Prolonging GRE lifetime: the optimization of communication protocol and power sources enable the maximum device lifetime of 20.1 d when configured to perform temperature measurement at an hourly interval. Inset shows bar charts demonstrate the average lifetime of GRE when maintained at three different modes of operation. The graph shows the in vitro experimental data of temperature measured when the device is left in a convection oven maintained at 37 °C over 19.5 d.