Polymer membranes for continuous analyte sensors
Devices and methods are described for providing continuous measurement of an analyte concentration. In some embodiments, the devices include a membrane that has an interference domain designed to reduce the permeation of one or more interferents.
1. An implantable device for continuous measurement of an analyte concentration, the implantable device comprising:
a sensor configured to generate a signal indicative of a concentration of an analyte in a host; and
a membrane located over the sensor, the membrane comprising a first domain configured to reduce a flux therethrough of the analyte, a second domain that comprises an enzyme, and a third domain configured to reduce passage therethrough of an interferent, the third domain comprising a plurality of alternating polyelectrolyte layers, wherein the device is configured to exhibit a selectivity for acetaminophen over hydrogen peroxide of less than about 0.005, wherein the selectivity is determined by dividing a sensitivity of the device for acetaminophen by a sensitivity of the device for hydrogen peroxide, wherein the acetaminophen sensitivity is determined in vitro by measuring the device's current response versus concentrations of acetaminophen at 10 μM aqueous acetaminophen, 50 μM aqueous acetaminophen, and 100 μM aqueous acetaminophen, and then performing linear regression, and wherein the hydrogen peroxide sensitivity is determined in vitro by measuring the device's current response versus concentrations of hydrogen peroxide at 1 μM aqueous hydrogen peroxide, 2 μM aqueous hydrogen peroxide, and 3 μM aqueous hydrogen peroxide, and then performing linear regression.
2. The implantable device of claim 1 , wherein the plurality of alternating polyelectrolyte layers of the third domain comprise two types of layers.
3. The implantable device of claim 2 , wherein the two types of layers comprise a polycationic layer and a polyanionic layer.
4. The implantable device of claim 3 , wherein polycationic layers form the most distal layer and the most proximal layer of the third domain with respect to the sensor.
5. The implantable device of claim 4 , wherein the third domain comprises an odd number of alternating polyelectrolyte layers.
6. The implantable device of claim 5 , wherein the third domain comprises at least three alternating polyelectrolyte layers.
7. The implantable device of claim 6 , wherein the first and third most distal layers with respect to the sensor are polycationic layers, and wherein the second most distal layer with respect to the sensor is a polyanionic layer.
8. The implantable device of claim 5 , wherein the third domain comprises at least five alternating polyelectrolyte layers.
9. The implantable device of claim 2 , wherein the two types of layers comprise a first layer type configured to selectively reduce passage therethrough of a first interferent and a second layer type configured to selectively reduce passage therethrough of a second interferent.
10. The implantable device of claim 1 , wherein the plurality of alternating polyelectrolyte layers comprise at least three types of layers or bilayers.
11. The implantable device of claim 10 , wherein the at least three types of layers or bilayers comprises a first layer or first bilayer type configured to selectively reduce passage therethrough of a first interferent, a second layer or second bilayer type configured to selectively reduce passage therethrough of a second interferent, and a third layer or third bilayer type configured to selectively reduce passage therethrough of a third interferent.
12. The implantable device of claim 1 , wherein the first domain is distal to the second domain with respect to the sensor, and wherein the second domain is distal to the third domain with respect to the sensor.
13. The implantable device of claim 1 , wherein the sensor comprises an electroactive surface, and wherein the third domain contacts the electroactive surface.