David Lipson

In vivo evaluation of an electroenzymatic glucose sensor implanted in subcutaneous tissue

Cleanroom processing techniques have been used to mass-produce flexible, electroenzymatic glucose sensors designed for implantation in subcutaneous tissue. In vitro characterization studies have shown the sensors performance to be acceptable. Initial in vivo studies were conducted with the sensor implanted in the subcutaneous tissue of rabbits. Sensors implanted in the subcutaneous tissue of normal human subjects showed an excellent correlation between glucose concentrations measured by the sensor and capillary finger sticks measured with a commercial analyzer.

An electroenzymatic glucose sensor fabricated on a flexible substrate

Abstract A glucose-oxidase-based electroenzymatic glucose sensor has been developed using thin-/thick-film processing techniques. We believe that this processing scheme will overcome a major impediment to the successful movement of the devices from the research laboratory to the marketplace by removing the difficulty of fabricating large numbers of reproducible and economical sensors. Several hundred sensors have been fabricated and tested in vitro. The sensors respond linearly to glucose, are stable for 72 h, are oxygen independent and have a 90 s response time. The sensors have also responded appropriately during preliminary glucose tolerance tests performed in rabbits.

Microfabrication Of Reproducible, Economical, Electroenzymatic Glucose Sensors

We present a method for fabricating electroenzymatic glucose sensors. The general approach i s to utilize thin- and thick-film deposition techniques similar to those used in the semiconductor processing industry. The sensors are fabricated in lots of 130, with the goal of a cheiving r eproducible s ensor performance and economical fabrication costs, using processes that can be readily up-scaled for manufacturing large numbers of sensors. The sensors are formed on a flexible substrate to provide less irritation and longer, more reliable operation when placed in vivo. Sensor operation has been characterized in vitro, and sensor performance has been found to meet

Multifiber, multiwavelength, fiber optic fluorescence spectrophotometer

A fibreoptic spectrofluorimeter capable of remote operation of up to 18 biosensors under fully automated, multiplexed control was constructed. Excitation and emission wavelengths were separately adjustable, as were optical bandwidths, signal gain, phase, integration time, and illumination duty cycle. Synchronous demodulation was used to enhance signal-to-noise ratio and allow operation under ambient lighting conditions. Detection limit for aqueous sodium-fluorescein was below 1 ng/mL at greater than unity signal-to-noise ratio, with effective sampling volumes less than 0.02 mu L. The fluorimeter showed characteristic fiberoptic sampling behavior with asymptotic nonzero signal magnitudes under increasing path-length conditions.<<ETX>>

Preliminary clinical results from an electroenzymatic glucose sensor implanted in subcutaneous tissue

A glucose-oxidase based electroenzymatic glucose sensor has been developed using thin/thick film processing techniques. This processing scheme has provided the ability to mass-produce the sensors in a cost effective and reproducible manner. The small, flexible sensors are designed for implantation in the subcutaneous tissue. Previous in vitro characterization studies and in vivo rabbit studies have shown the sensors performance to be acceptable. Glucose measurements obtained with sensors implanted in the subcutaneous tissue of normal human subjects showed an excellent correlation with glucose measurements obtained from capillary, finger-stick blood and intravenous blood.

Drilled optical fiber sensors: a novel single-fiber sensor

The key to a successful fiber optic sensor design is to maximize the interaction between the optical radiation carried in the waveguide and the chemical species. Of the various designs that have been discussed evanescent and end fire have been the most widely used in chemical sensing. These approaches are best with fluorescent chemistry systems. Absorbance based optical fiber sensing systems offer the advantages of being adaptable to a wider variety of sensing chemistries. Historically single fiber systems for absorbance sensing have not been feasible without having an external mirror attached to the fiber end. The external attachment of the sensing chamber and mirror increase the size fragility and cost of the sensor. We have developed a novel single fiber sensor that shapes the end of the fiber into an optical element and places the chemistry within the fiber itself.