Stabilised Biosensing Using Needle‐Based Recess Electrodes

Abstract

A recess disk electrode for amperometric monitoring of oxygen and glucose is reported. The basic design of sensor is a needle structure for easy implantation, embodying a gold filled silica capillary with a 80 mu m inner diameter working electrode. Recess and inlaid disc electrodes, placed inside stainless steel tubes which served as a counter/reference electrode, were compared. The working electrode surface was modified with different treatments and barrier membranes to achieve selectivity for the analytes of interest. The basic needle format is ideal for in vivo use, and the format is easily extendable to other analyte targets. The sensors show linear working range for oxygen up to 160 mmHg partial pressure of oxygen, and for glucose from 1 to 10 mM. Bio-fouling, as assessed by exposure to bovine serum albumin, was significantly reduced. Response times for the recess construct was increased but remained within the acceptable range for physiological monitoring. The operational stability of the sensors is demonstrated as well as the interference-free detection of peroxide in the presence of physiologically relevant levels of ascorbic acid, uric acid, acetaminophen, and catechol. Preliminary in vivo tests showed excellent response towards glucose

Electrochemical Monitoring of Subcutaneous Tissue pO2 Fluctuations during Exercise Using a Semi‐implantable Needle Electrode

“…Surface contamination was not completely avoided on the basis of response, but stability was adequate for in vivo studies. Without a membrane, bare electrode response decreases by 40 % under the same conditions [41]. Figure 2A shows the oxygen calibration curve for the physiological range 0 to 160 mm Hg measured in a phosphate buffer saline (PBS) and 40 mg/ml BSA.…”

“…Reliable operation of such devices is entirely dependent on a diffusion control element definitively residing in the sensor and not the surrounding sample matrix [21,22]. We have previously investigated PTFE, silicones and polyurethanes for oxygen selectivity and permeability [40,41] and for resistance to biofouling. Polyurethane (Trixene SC7602) was chosen here, as it conferred the desired linear response over the physiological range (0-160 mm Hg pO2), the level of permeability needed for electrolyte access from the sample and relatively short response times; 5 min for a plateau response.…”

An electrochemical study of acrylate bone adhesive permeability and selectivity change during in vitro ageing: A model approach to the study of biomaterials and membrane barriers

“…The final steady state outcome is an equilibrium hydration state [ [59] , [60] , [61] ] defining general permeability behaviour. This is well recognised in the case of membrane based biosensors, where stable permeability and selectivity is attained within minutes on exposure to a sample and which, in the absence of fouling, offers relatively stable permeability and therefore response [ 62 , 63 ]. Water ingress prior to equilibration causes an accelerated permeability change which is known to have an exponential profile [ 64 ], and this was exactly observed for the hydrating adhesive polymers here.…”

Sensors for Fetal Hypoxia and Metabolic Acidosis: A Review

“…Another impediment to electrochemical lactate measurement accuracy is the presence of common electroactive interferents such as acetaminophen, ascorbic acid, and uric acid, which adversely affect the specificity of in-vivo electrochemical sensors [ 49 , 50 ]. Recent studies have demonstrated that this interference can be minimized through either the use of compensation electrodes and direct electron transfer [ 50 ] or modification of the electrode material [ 49 , 51 , 52 ].…”