Guanine Cytosine (GC)-rich DNA/PNA microbolometer

Details Guanine Cytosine (GC)-rich DNA/PNA microbolometer Guanine Cytosine (GC)-rich DNA/PNA microbolometer

1998-09-18

2001-07-10

Hannaher, Constantine (Department: 2878)

Radiant energy

Invisible radiant energy responsive electric signalling

Infrared responsive

C250S338300, C250S306000

Reexamination Certificate

active

06259096

ABSTRACT:

FIELD OF THE INVENTION
This invention is related to the field of uncooled infrared (IR) detector technology, and it particularly demonstrates the use of thin film structures on oxidized silicon consisting of Guanine Cytosine (GC)—rich double-stranded DNAs and peptide nucleic acid (PNAs) helices and the current CMOS electronic circuits for optimizing the IR detector performance of uncooled microbolometer technology. PNA are a new class of DNA mimics in which the regular nucleotide of adenine, thymine, cytosine and guanine are connected via a peptide-like backbone (Ref 1). PNA molecules retain the same Watson-Crick base pairing as regular oligonucleotides, with the added benefits of resistance to enzyme digestion, therefore extending its shelf life indefinitely. It is anticipated that DNA /or PNA molecules rich in GC base pairs would exhibit relatively high temperature coefficient of resistance near their melting temperature as compared with naturally occuring Watson-Crick B-form of DNAs because of the three hydrogen bonds associated with the GC base pairs in the double-stranded helical structure, allowing excellent IR imaging capability in night vision devices. The predicted performance of such DNA microbolometer on oxidized silicon will certainly exceed the short range limit of the present VOx microbolometer technology currently employed in military service and it will even compete with the expensive cooled staring systems in most applications.
BACKGROUND INFORMATION
Applicant's invention pertains to a Thermal Infrared Detector of the thin film resistance bolometer type, wherein IR radiation incident on the bolometer is absorbed, resulting in a temperature rise of the detector material and therefore a change in the resistance of the bolometer detector material, which can then be transmitted or recorded by currently available CMOS circuits. Thin film bolometer infrared detectors using proteins of high dipole moment are described by the present author in recent US Patent No ARL-98-46 and others using either VO
x
or semiconductors are described in U.S. Pat. Nos. 4,574,263; 4,116,063 and 3,069,644 respectively. However, the proposed biological microbolometer made of GC-rich double-helical DNAs or PNAs is expected to provide much higher IR detecting capability as compared with the conventional micro-bolometer made of VO
x
materials.
BRIEF SUMMARY OF THE INVENTION
This invention improves the sensitivity and resolution of the present uncooled microbolometer technology by sufficiently increasing TCR properties of the detecting elements by simply replacing VO
x
or semiconductors with thin films of GC-rich DNAs and PNAs. The temperature coefficient of resistance (TCR) properties defined as TCR=1/R (dR/dT) where R is the material resistance at the operating temperature T. Routinely obtained TCR values for VO
x
are close to −2.5%/deg C and TCR values of proteins are of the order of +5% to 8.0%/° C. The B-form of DNAs are expected to exhibit a sharper break in conductivity when it denatures, since it converts from a double-stranded helix to a random coil. DNAs and PNAs rich in GC base pairs seem to provide even better TCR values when they denature because of the three hydrogen bonds associated with the GC base pairs (see FIG.
1
). As a result GC rich DNAs and PNAs are supposed to exhibit higher sensitivity in IR detection as compared with the other materials proposed in the patent applications cited in this text.


REFERENCES:
patent: 5389475 (1995-02-01), Yanagisawa et al.
patent: 5629665 (1997-05-01), Kaufmann et al.
patent: 91/16607 (1991-10-01), None

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