Composite detection devices having in-line desalting and methods of making the same

A sensing system configured for in-line desalting of an analyte stream and sensing an analyte in the desalted analyte stream, comprising:

• a microfluidic device comprising;
• one or more microfluidic channels configured to define a flow direction of the analyte stream, wherein at least one microfluidic channel of the one or more microfluidic channels is configured for localized desalting, bulk desalting, or a combination thereof, and wherein a height of a portion of the at least one microfluidic channel of the one or more microfluidic channels configured for the localized desalting is more than a height of a portion of the at least one microfluidic channel configured for the bulk desalting;
• a porous silicon microfluidic membrane having a surface that comprises a plurality of nanopores, wherein each of the plurality of nanopores comprises an upper opening into an interior portion of the at least one microfluidic channel, and wherein the plurality of nanopores is configured for at least partially desalting the analyte stream;
• and
• a silicon nano sensor having a surface that faces the interior portion of the at least one microfluidic channel, wherein the silicon nanosensor is located downstream from the porous silicon microfluidic membrane in the flow direction of the analyte stream for sensing the analyte disposed adjacent to the porous silicon microfluidic membrane, and
• wherein the nanosensor is in communication with a signal processing unit.

A bio-sensing system configured for in-line desalting of an analyte stream and sensing an analyte in the desalted analyte stream, comprising:

• a bio-sensing device comprising a microfluidic device, wherein the microfluidic device comprises:
• at least one microfluidic channel that defines a flow direction of the analyte stream, wherein the at least one microfluidic channel is configured for localized desalting, bulk desalting, or a combination thereof, and wherein a height of a portion of the at least one microfluidic channel configured for the localized desalting is more than a height of a portion of the at least one microfluidic channel configured for the bulk desalting;
• a porous microfluidic membrane having a surface that comprises a plurality of nanopores, wherein each of the plurality of nanopores comprises an upper opening into an interior portion of at least one of the at least one microfluidic channel, and wherein the plurality of nanopores is configured for at least partially desalting an analyte solution by diffusion;
• a nano sensor having a surface that faces the interior portion of the at least one of the at least one microfluidic channel, wherein the nanosensor is located downstream from the porous microfluidic membrane in the flow direction of the analyte stream and wherein a change in electrical conductivity of the nanosensor indicates a detection of the desalted analyte solution by the nano sensor;
• and
• a signal processing unit in communication with the nanosensor for detecting the change in electrical conductivity of the nano sensor upon sensing the analyte.

A point of care diagnostic device comprising a sensing system for in-line desalting of an analyte stream and sensing an analyte in the desalted analyte stream, wherein the sensing system comprises:

• a microfluidic device comprising:
• at least one microfluidic channel configured to define a flow direction of the analyte stream, wherein the at least one microfluidic channel is configured for localized desalting, bulk desalting, or a combination thereof, and wherein a height of a portion of the at least one microfluidic channel configured for the localized desalting is more than a height of a portion of the at least one microfluidic channel configured for the bulk desalting;
• a microfluidic membrane having a surface that comprises a plurality of nanopores, wherein each of the plurality of nanopores comprises an upper opening into an interior portion of the at least one microfluidic channel, and wherein the microfluidic membrane is configured for desalting at least a portion of the analyte stream;
• and
• a nanosensor having a surface that faces the interior portion of the at least one microfluidic channel, wherein the nanosensor is located downstream from the microfluidic membrane in the flow direction of the analyte stream, wherein the nanosensor is configured for sensing a bio-molecule or a bio-molecule interaction in the desalted analyte stream, and wherein the nanosensor is in communication with a signal processing unit.