EPSIS (Electroconductive Polymer Sensor Interrogation System)

Model EPSIS 240 II US

Model EPSIS 240 II CS

EPSISoft Release 2.0

for B i o s e n s o r A s s a y s

Introduction and Background

Applications of EPSIS

Technical Specifications

Principle

Application Notes

Price List

Introduction and Background

The EPSIS 240II now boasts a new hardware configuration for software selectable two electrode and three electrode modes of sensor interrogation. This is a key and important development. With the two electrode mode, the user may now reliably and conveniently interrogate conductive polymer gas and vapor phase analytes -- useful in the development of electronic noses and VOC sensors - without resorting to previous electrode patch-ins. EPSIS continues, in its three-electrode mode, to offer its innovative electroconductive polymer sensor interrogation configuration for the development of conductimetric chemical sensors and biosensors.
EPSIS is the first of its kind sensor interrogation system designed specifically for research and applications-specific product development of chemical and biological sensors based on electroconductive polymer sensor technology. EPSIS is based on a patented analytical method that combines potentiometric, potentiostatic, and superior pulsed DC chronocoulometric capabilities in one unit. These electrochemical capabilities are sequentially combined to provide a powerful and versatile detection and measurement scheme that is unique to electroconductive polymer transducers. The result is a conductimetric response that detects, measures, and reports changes in electrical conductivity as electroconductive transducers respond to specific analytes to which they have been rendered chemically or biologically specific.

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Applications of EPSIS

EPSIS is a research and development instrumentation platform, comprising hardware and software tools, that is designed to aid you in your research and product development. EPSIS frees you from instrumentation development, allowing you to concentrate on the business end of things -- the sensing element itself. With EPSIS you can concentrate on developing your proprietary materials, sensor configuration and assay protocol.

  • EPSIS Applications in Chemical and Biological Sensor Development
    Ø In the development of chemical sensor and biosensor devices and systems: The high sensitivity of electroconductive polymer thin films to changes in redox state, along with the solid state construction and small device size, make these devices ideally suited for research and development of chemical and biosensor applications. The chemical specificity of chemical sensors may be derived form the use of various indicator agents including: macrocyclic agents and other inorganic binding compounds, metal occlusions, and inorganic catalysts. The biological specificity of biosensor devices may be conferred by the use of immobilized co-factors, enzymes, antibodies, enzyme-antibody conjugates, stabilized receptors, and DNA fragments.

  • EPSIS Applications in Gas and Vapor Phase Sensors
    Ø In the development of volatile organic compound (VOC) gas and vapor sensors and electronic noses: The ability of electroconductive polymers to reversibly absorb and desorp organic vapors from within their microstructure with simultaneous change in electrical conductivity makes these sensors well suited for the development of VOC probes. EPSIS boasts a unique two-electrode conductimetric mode suited for the study of the chemoresistive responses derived from electroconductive polymer-vapor interactions. Combined with our gas-vapor sorption cell, EPSIS multiplexes between two sensing elements located on the same chip.

  • EPSIS Applications in Polymer Materials Characterization
    Ø In the characterization of novel electroconductive polymers and other chemically responsive polymers:     EPSIS is conveniently used to study the electrical properties of various novel electroactive polymer films and polyelectrolyte gels. Studies such as: the potential dependence of the electrical conductivity; the ensuing open circuit or poise potential as a function of impressed polarization potential; electrical conductivity as a function of counter anion type and concentration, and dynamic conductivity changes arising from various environmental factors such as pH, temperature, etc.

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Technical Specifications

EPSIS 240II

EPSISoft 2.0

Technical Features

Specifications

Chemoresistance Range

10 Ohm to 2 M Ohm

Chemoresistance Resolution

+/- 0.3 %

Potential Range

-2,048 to +2,048 mV

Potential Resolution

+/- 1 mV

Ten (10) User-selectable Current Measuring Scales

0.5 to 500 micro A/V

Response Time

2 micro s

A/D Converter

12 bit resolution

Software Selectable Gain

1, 10, 100, 500

A/D Converter Throughput (speed)

45 KHz (22 *s) 2.5 KHz (400 *s)

Compliance Voltage

+/- 12 V at 10 mA

Maximum Current

10 mA

Weight, EPSIS 240U Analog Unit

1.6 Kg (2 lbs 4 ozs)

Dimensions, EPSIS 240U Analog Unit

14 cm W x 4 cm H x 19.5 cm D

EPSIS 240II CS

Multimedia PC

200 MHz

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Principle of Operation

EPSIS is designed to measure the chemoresistance responses of EPME devices, Bioanalytical Biosensors, and Electriochemical Biosensors.

    Ø Electroactive polymers such as, polypyrrole, polyaniline, and poly(3-hexylthiophene) display very dramatic changes in electrical (electronic) conductivity upon oxidation or reduction. The oxidation/reduction reactions of these polymers may be driven by an impressed electrode potential or by the chemical potential energy of a chemical oxidizing or reducing agent. The resulting electrical conductivity of these chemically sensitive polymers (under controlled circumstances) is precisely governed by the state of charge or extent of oxidation/reduction of the polymer. These features identify electroconductive polymers as transducer-active materials well suited to chemical and biological sensor applications. EPSIS is based on the simple principle that the amount of current (or charge) traversing a fixed dimension of electroconductive polymer film may be modulated by the chemical potential energy (concentration) of an analyte with which it is in intimate contact and to which it has been rendered specific. EPSIS uses this chemoresistance principle and exploits the very large changes in electrical impedance which accompanies the mediated oxidation/reduction of electroactive polymers fabricated on interdigitated microsensor electrodes.

    Ø EPSIS uses a patented analytical method which first evaluates the integrity of the electroconductive polymer device, initializes it to a user specified extent of charge to establish a known and reproducible starting electrical conductivity, then interrogates it with non-pertubating, small amplitude, short duration pulses to reveal time dependent changes in electronic conductivity as the device responds to an analyte. Sensor responses may be kinetic when the rate of change in electrical conductivity is monitored or equilibrium when the extent of change in electrical conductivity is monitored.

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Application Notes

For further information, request Application Notes:

Ø IME1 - Interdigitated Microsensor Electrodes: Applications and References.
Ø IME2 - Conductimetric Urea Biosensor Formed From Interdigitated Microsensor Electrodes
Ø IME3 - Cleaning Procedures

Electroconductive Polymer Microsensor Electrode (EPME(TM)) is the trade name for a family of non-specific sensor devices developed by ABTECH.

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