MICRODISC ELECTRODE ARRAYSTM (MDEAs) (Microfrabricated Disc Electrode Arrays (IDAs))

MDEA DEVICES	Disc dimensions / Number of Discs	Active Area	Conductor
MDEA 360	3,600 microns diameter discs / 1 disc	0.10 cm2	Au, Pt, ITO
MDEA 250	250 microns diameter discs / 207 microdiscs	0.10 cm2	Au, Pt, ITO
MDEA 100	100 microns diameter discs / 1,296 microdiscs	0.10 cm2	Au, Pt, ITO
MDEA 050	50 microns diameter discs / 5,184 microdiscs	0.10 cm2	Au, Pt, ITO

	MDEA Brochure (PDF)	MDEA Prices	Price List
Introduction and Background	Applications of MDEAs	Technical Specifications	MDEA Accessories	Methods	Application Notes

Introduction and Background Ø Microdisc Electrode Arrays (MDEAs) are inert, array microelectrodes formed from a microlithographically patterned insulator-on-conductor-on-insulator configuration. They are designed for the study of electrochemical and optical properties of thin polymeric films and coatings, for applications in microelectrochemistry, for electrical/electrochemical impedance spectroscopy, and for chemical and biological sensor development. Ø Microfabricated from 100 nm magnetron sputter-deposited gold, e-gun vapor-deposited platinum, or conductive indium tin oxide (ITO) on an electronics grade borosilicate glass, these devices are supplied in three microdisc diameters and corresponding microdisc densities. A 500nm thin silicon nitride layer is applied over the conductor and is microlithographically windowed using reactive ion etching to reveal an array of micro-windows to the metal beneath and a bonding pad. MDEAs are avalable as packaged (with attached leadwires and encapsulated) or as un-packaged die. Ø MDEA chips of gold, platinum, or ITO are available with 50 microns, 100 microns, 250 microns, or 3,600 microns disc diameter. Ø In research and product development, these devices are widely used for conductimetric, chemoresistive chemical and biological sensors using electrically conducting (electroconductive) polymers, for impedance sensors based on Langmuir-Blodgett thin films, for studying environmental effects on polymer thin films, and in modern micro-electrochemistry. Ø Investigate the chemoresistive responses of transducer-active, polymeric thin films in the same electrode configuration, the same test environment, and on the same sample film. Develop these devices into products where the application requires a compact, durable and versatile chemical or biological chemoresistive or electroanalytical sensor of low cost. Back to Index Applications of MDEAs Applications of MDEAs in research and product development include: Ø As conductimetric chemical sensors and biosensors based on electroactive polymers. Such devices exploit the very large change in electrical impedance that accompanies oxidation/reduction of these polymer films. Films are conferred with chemical and biological specificity through the use of inorganic catalysts, organic hosts-guests binding compounds, synthetic antibodies, or molecularly imprionted polymers, and natural biorecognition agents such as enzymes, antibodies and DNA. Ø For the study of electrical and electrochemical impedance spectroscopy of organic thin films and coatings and carbon nanotubes. Ø As a capacitance probe during the deposition or cure of an organic thin film or polymer e.g. Films based on Langmuir-Blodgett thin film deposition or cure of an epoxy. Ø In modern microelectrochemistry -- as generator and collector electrodes in electrochemical amplification or in the performance of electroanalysis in high impedance environments. The microdisc electrode format allows accommodates radial diffusion . Ø In conductimetry studies. To determine the conductance of low conductivity media and in conductimetric titrations. Ø In coatings research and development. For example, to study the transport of water into and through a coating or to study the physical aging of the polymer upon environmental exposure or accelerated aging. Back to Index Technical Specifications
	Ø Chip Substrate:	Schott D263 Borosilicate Glass
		Dielectric Constant, Epsilon(r) at 1 MHz			6.7
		Dielectric Loss Angle, tan delta, at 1 MHz			61 x 10-4
		Electrical Resistivity (50 Hz) (250 C)			1.6 x 10^8 ohm cm
		Coefficient of Linear Thermal Expansion, * 20-300 Deg C			7.2 x 10^-6 K^-1
		Refractive Index at 20 C, ne ( Lambda = 546.1 nm)			1.5249
	Ø Metallization:	100 Å Ti|W / 1000 Å Au or Pt and ITO = 10 Ohms/sq
	Ø Insulating Top Layer:	Silicon Nitride (Si3N4)
				No of Discs		Electroactive Area (cm2)		Geometric Area (cm2)
	Ø MDEA 360		A single disc, 3.60 mm in diameter.	1		1.0 x10-1		1.0 x10-1
	Ø MDEA 250		207 separate discs, each 250 mm in diameter and arranged 500 mm on centers in a hexagonal close packaed array.	207		1.0 x10-1		4.5 x10-1
	Ø MDEA 100		1,296 separate discs, each 100 mm in diameter and arranged 200 mm on centers in a hexagonal close packaed array.	1,296		1.0 x10-1		4.5 x10-1
	Ø MDEA 050		5,184 separate discs, each 50 mm in diameter and arranged 100 mm on centers in a hexagonal close packaed array.	5,184		1.0 x10-1		4.5 x10-1
	Ø MDEA Chip Dimensions		Un-packaged Die	Packaged Die
			(l x w x t)	(l x w x t)
	MDEA XXX		2.00 x 1.00 x 0.05 cm	13.2 x 1.38 x 0.7 cm
	Ø Packaging
	Electrode Body:		PVC-Jacketed printed circuit board
	Encapsulant:		Epoxy header. Polyimide packaged chip.
	Leadwires:		Color coded, 28 AWG stranded copper, shielded, and PVC jacketed
Back to Index

MDEA Accessories
	Wand	Test Clip
Lead Length	4.5 cm	N/A
Connector Type	Gold Plated	Gold Plated Pins
Number of Conductors	4	4
Lead	Rigid Wand	N/A
Part No.	WAND	STC

 Back to Index

Methods Ø Films or coatings may be applied to the MDEA device by dip coating, spin casting, spray painting, air-brushing, brush painting, by Langmuir-Blodgett thin film deposition technique, by electropolymerization, and/or by molecular self assembly. Ø The chip may be immersed in organic, or aqueous medium to a level above the geometric area occupied by microdiscs. Ø Electrical contact is made via bonding pad loacaed on on end of the chip.   Back to Index Application Notes For further information, request Application Notes or you may download application note files: Microdisc Electrode Array (MDEATM) is the tradename for a family of devices developed by ABTECH. Also called microelectrode arrays, these devices are microfabricated (using microelectronics fabrication techniques) to form patterns of conductors deposited on an insulating substrate chip. Back to Index

Contact: Ann M. Wilson, Manager,
Applications Development ABTECH Scientific, Inc.
911 East Leigh Street G24, Richmond, Virginia 23219
Telephone Number: +1-804-783-7829 Fax Number: +1-804-783-7830
e-mail: sales@abtechsci.com

Last Revision 07/20/2004, (c) 2000-2004 ABTECH Scientific, Inc.