Atomic Force Microscopy Structural Characterization of Polyaniline Thin Film Sensors

1994 ◽  
Vol 338 ◽  
Author(s):  
Jack Y. Josefowicz ◽  
Frederick G. Yamagishi ◽  
Camille I. van Ast
Keyword(s):  
Atomic Force Microscopy ◽  
Response Time ◽  
Gold Electrodes ◽  
Lower Sensitivity ◽  
Force Microscopy ◽  
Thin Film Sensors ◽  
Atomic Force ◽  
Polymer Sensors ◽  
Modeling Analysis ◽  
Low Concentrations

ABSTRACTUsing Tapping Mode Atomic Force Microscopy (TMAFM), the surface structure was determinedfor polymer sensors which incorporated polyaniline (PAn) films that were deposited electrochemically across narrow insulating gaps between interdigitated gold electrodes. The sensitivity and response time for such sensors, which can be used for the detection of low levels of gases and low concentrations of impurities in liquid media critically dependon the quality and structure of the polymer film in the gap region between the gold electrodes. TMAFM images of the PAn films ranging in thickness between ≈1.5μtmand ≈5μm reveal that films approaching 5μm (typically used in such sensors) develop deep cracks at the edges and along the length of the Au electrodes. Thecracks, which appear to be a consequence of stress build-up in thick films, can lead to reliability problems and inferior sensor performance. Simple modeling analysis of cracked films indicates that they can lower sensitivity and increase response time. TMAFM images of sensors with thinner ≈2.5μm PAn films show no cracks as well as continuous PAn bridges across the gap between Au electrodes. Analyses of TMAFM images are presented and compared for thin and thick film PAn sensors.

Submicron Electrode Gaps Fabricated by Gold Electrodeposition at Interdigitated Electrodes

2014 ◽  
Vol 605 ◽  
pp. 107-110
Author(s):  
M.J.J. van Megen ◽  
W. Olthuis ◽  
A. van den Berg
Keyword(s):  
Atomic Force Microscopy ◽  
Gold Layer ◽  
Electrode Spacing ◽  
Gold Electrodes ◽  
Interdigitated Electrodes ◽  
Force Microscopy ◽  
Atomic Force ◽  
Gap Spacing

Electrodes with submicron gaps are desired for achieving high amplication redoxcycling sensors. In this contribution we report the use of electrodeposition of gold in order todecrease the inter-electrode spacing at interdigitated electrodes. Using this method submicronspacings can be obtained without expensive techniques such as e-beam lithography or focusedion beam milling. Initially, gold interdigitated electrodes with a nger spacing of 2.5 m wererealized by lift-o processing. Using a commercial gold sulphite bath (ECF64D) and 100 mscurrent pulses of -1.78 A, these gold electrodes were plated with an additional gold layer. Asa result, the inter- electrode spacing, as measured using atomic force microscopy and conven-tional microscopy, was reduced to 0.6 m. The achieved gap spacing is limited by electrodeimperfections resulting from the lift-o process. At these imperfections the electrodes becomeshorted. Additional experiments with wet etched electrodes are expected to yield smaller gapspacings

scholarly journals Irreversible chemical afm-fishing for the detection of low-copied proteins

2014 ◽  
Vol 60 (1) ◽  
pp. 28-50 ◽  
Author(s):  
Yu.D. Ivanov ◽  
V.V. Danichev ◽  
T.O. Pleshakova ◽  
I.D. Shumov ◽  
V.S. Ziborov ◽  
...  
Keyword(s):  
Experimental Data ◽  
Atomic Force Microscopy ◽  
Theoretical Model ◽  
Horseradish Peroxidase ◽  
Bulk Solution ◽  
Irreversible Binding ◽  
Chip Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Low Concentrations

The atomic-force microscopy-based method of irreversible chemical AFM-fishing (AFM-IF ) has been developed for the detection of proteins at ultra-low concentrations in solution. Using this method, a very low concentration of horseradish peroxidase (HRP) protein (10 17 M) was detected in solution. A theoretical model that allows the description of obtained experimental data, is proposed. This model takes into consideration both the transport of the protein from the bulk solution onto the AFM-chip surface and its irreversible binding to the activated area.

scholarly journals Imaging of viscoelastic soft matter with small indentation using higher eigenmodes in single-eigenmode amplitude-modulation atomic force microscopy

2018 ◽  
Vol 9 ◽  
pp. 1116-1122 ◽  
Author(s):  
Miead Nikfarjam ◽  
Enrique A López-Guerra ◽  
Santiago D Solares ◽  
Babak Eslami
Keyword(s):  
Atomic Force Microscopy ◽  
Amplitude Modulation ◽  
Soft Matter ◽  
Short Paper ◽  
Lower Sensitivity ◽  
Viscoelastic Materials ◽  
Force Microscopy ◽  
Atomic Force ◽  
Oscillation Frequencies ◽  
Small Indentation

In this short paper we explore the use of higher eigenmodes in single-eigenmode amplitude-modulation atomic force microscopy (AFM) for the small-indentation imaging of soft viscoelastic materials. In viscoelastic materials, whose response depends on the deformation rate, the tip–sample forces generated as a result of sample deformation increase as the tip velocity increases. Since the eigenfrequencies in a cantilever increase with eigenmode order, and since higher oscillation frequencies lead to higher tip velocities for a given amplitude (in viscoelastic materials), the sample indentation can in some cases be reduced by using higher eigenmodes of the cantilever. This effect competes with the lower sensitivity of higher eigenmodes, due to their larger force constant, which for elastic materials leads to greater indentation for similar amplitudes, compared with lower eigenmodes. We offer a short theoretical discussion of the key underlying concepts, along with numerical simulations and experiments to illustrate a simple recipe for imaging soft viscoelastic matter with reduced indentation.

Fabrication of Submicrometer-Sized Gold Electrodes of Controlled Geometry for Scanning Electrochemical-Atomic Force Microscopy

2002 ◽  
Vol 74 (24) ◽  
pp. 6355-6363 ◽  
Author(s):  
Jeremy Abbou ◽  
Christophe Demaille ◽  
Michel Druet ◽  
Jacques Moiroux
Keyword(s):  
Atomic Force Microscopy ◽  
Gold Electrodes ◽  
Force Microscopy ◽  
Atomic Force
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