NSF-ITR Meeting 10-05 Miniaturized Sensors Air molecules aerosols Water molecules

NSF-ITR Meeting 10-05

Miniaturized Sensors

Airmoleculesaerosols

Watermoleculescells, viruses

Sensor Operation

Sensor Specific Initial event

Transduction to a signal

Measurement of signal

Communication of result

Initial Event

Binding of analyte

Interrogation of free analyte

Chemical reaction

Binding of Analyte

GasChemical or physical adsorption

Metal oxides & semiconductors

BiologicalsAntibodiesNucleic acidsLigands

Interrogation of free analyte

GasIonizationSpectroscopy

Light, microwave, massWater

SpectroscopyLight, microwave, mass

Transduction to a SignalElectrical

ConductanceImpedance spectroscopyvoltametry

Light & MicrowavesAbsorptionFluorescence

Resonance OscillatorsMechanical motionSurface acoustic waves

Gas Ionization

Modi, et al., Nature, 424, 171-174, 2003

Gas Ionization

Modi, et al., Nature, 424, 171-174, 2003

Complex Mixtures

Difficult to distinguish components

Signal of one component can swampothers

Difficult to standardize

A Possible Solution

Fractionate the analyte stream

Differentiate molecules based on size, shape or charge

On-chip family of membranes

On-chip Family of Membranes

Controlled filtration characteristics

Pattern membrane characteristics

Biocompatible

Use with or without electrophoresis

Two Membrane Types Under Evaluation

Cellulose AcetateSpin cast

AluminaNanofabricated

Filtration Characteristics vs Preparation

Purification: DNA from HemeMembrane + electrophoresis

Mohamed, et al., Chromatography A, 2005

Proposed Selective Gas SensorOn-chip membrane & ionization

An Antibody Based Cell Sensor

Binding agent - immobilized antibody

Electrical measurement - impedance

Number of captured CD4+ cells vs Impedance

Mishra, et al., Biosensors & Bioelcectronics, 2005.

Amperometric biosensor using ion channel proteins

4 LAYERS

4. Protein: sensing component

3. Lipid membrane: provides the proper environment for the sensor proteins

2. Hydrogel: structural (localization and stability)

1. Electrode: Detection

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