Techniques to improve polyurethane membranes for implantable glucose sensors
The invention provides an implantable membrane for regulating the transport of analytes therethrough that includes a matrix including a first polymer; and a second polymer dispersed throughout the matrix, wherein the second polymer forms a network of microdomains which when hydrated are not observable using photomicroscopy at 400× magnification or less. In one aspect, the homogeneous membrane of the present invention has hydrophilic domains dispersed substantially throughout a hydrophobic matrix to provide an optimum balance between oxygen and glucose transport to an electrochemical glucose sensor.
1. A method for preparing an implantable homogeneous membrane, the method comprising the steps of:
forming a composition comprising a dispersion of a hydrophobic-hydrophilic polymer within a matrix of a hydrophobic polymer;
maintaining the composition at a temperature sufficient to maintain solubility of the hydrophobic-hydrophilic polymer and the hydrophobic polymer;
applying the composition at the temperature to a substrate to form a film thereon; and drying the film to form a membrane.
2. The method of claim 1 , wherein the composition forming step comprises forming a mixture or a blend.
3. The method of claim 1 , wherein the maintaining step comprises heating the composition at a temperature of about 70° C.
4. The method of claim 1 , wherein the drying step comprises drying at a temperature of from about 120° C. to about 150° C.
5. The method of claim 1 , wherein the hydrophobic-hydrophilic polymer comprises polyethylene oxide.
6. The method of claim 1 , wherein the hydrophobic polymer comprises polyurethane.