Fig. 4.

SEM images show the PMMA sensor (A) before immersion in blood, and 24 h after immersion in (B) arterial and (C) venous non-heparinised flowing animal blood. Spectra show relative quantity of elements detected (D) before in vivo insertion, and 24 h after continuous use in (E) arterial, and (F) venous blood. The elements detected did not appear different after immersion in blood, suggesting no clots had adhered to the sensors’ surface. C denotes carbon; O oxygen; and Si silicon, respectively.