BIOCOMPATIBILITY HEMOCOMPATIBILITY - IMPLICATIONS AND OUTCOMES FOR SENSORS

Sensors are a sample contacting technology, and when exposed to biolog ical matrices tend to suffer from the problem of poor biocompatibility and surface fouling. The effects are evidenced by time dependant sign al drift (particularly for those devices which are implanted intravasc ularly). Practical methods to reduce such effects require an understan ding of the interface between the electrode and its environment prior to assessment of the potential areas for improvement. Current procedur es employed to overcome the observed losses in electrode sensitivity ( following exposure to whole blood) include surface modification of the outer diffusion limiting membrane (via variation in film porosity) or even biomimicry of the fluid cell membrane. At amperometric electrode s incorporation of additional inner perm-selective membranes has achie ved a reduction in electrode passivation from undesirable surface acti ve compounds as has the use of low polarisation potentials. Other stud ies have attempted to induce an aqueous barrier between the matrix and the electrode tip which physically prevents passage of cellular compo nents from the sensor surface. Careful choice of the system and materi als will ultimately lead to biocompatible non-fouling devices capable of functioning in an array of bio-environments suitable for clinical m onitoring of the critically ill patient.