Akhil Moorthi - Academia.edu (original) (raw)

Papers by Akhil Moorthi

2012 IEEE Sensors, 2012

ABSTRACT A novel flexible surface enhanced Raman spectroscopy (SERS) substrate was successfully f... more ABSTRACT A novel flexible surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated by gravure printing silver (Ag) nanoparticle ink, with ~20-50 nm particle size, as metallization on flexible polyethylene terephthalate (PET). The capability of the fabricated SERS substrate to be used as a sensor for detecting toxic heavy metal compounds such as mercury sulfide (HgS) was demonstrated. An enhancement factor of 5 orders of magnitude was obtained when compared to the intensity of Raman spectrum of target molecules adsorbed on bare PET. This response demonstrated the feasibility of the novel SERS substrate to be used in applications for detection of toxic heavy metals. In addition, the effect of temperature on the intensity of the Raman spectrum was also tested. The result showed 85 % decrease in intensity at 85 °C, when compared with the intensity at 25 °C.

Sensors and Actuators B: Chemical, 2012

A novel surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated on a sil... more A novel surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated on a silicon wafer using inkjet printing. Silver (Ag) nanoparticle (NP) based ink, with average particle size of 150 nm, was inkjet printed on the surface of the silicon wafer. A thickness of 400 nm was measured for the printed Ag NP film using vertical scanning interferometry. The Ag NP printed SERS substrate was tested toward heavy metal compounds like cadmium sulfide (CdS), zinc oxide (ZnO) and mercury sulfide (HgS). An amplification of the SERS intensity by an order of 3-5 times was observed for all test samples, due to the presence of hotspots between the metal nanoparticle aggregates. The responses demonstrated the feasibility of the novel SERS substrate to be used in applications for detection of heavy metal compounds. (A. Eshkeiti). pursuing the MS degree in Electrical Engineering at Western Michigan University, Kalamazoo. His research interests include design, fabrication, and characterization of printed sensor structures, strain gauge sensors, and lab-on-a-chip sensing systems.

A novel flexible surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated... more A novel flexible surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated by gravure printing a thin film of silver (Ag) nanoparticle ink with 20~50 nm particle size on polyethylene terephthalate (PET). The feasibility of the fabricated SERS substrate for detecting toxic heavy metals such as mercury sulfide (HgS) and cadmium sulfide (CdS) was demonstrated. The SERS based response of the printed substrate produced an enhanced Raman signal when compared to target molecules adsorbed on bare PET. An enhancement factor of 5 orders of magnitude due to existence of hot spots between nanoparticles was obtained. This response demonstrated the feasibility of the novel SERS substrate to be used in applications for detection of toxic heavy metals.

This paper reports on the successful development of a fully printed wireless LC sensor for the de... more This paper reports on the successful development of a fully printed wireless LC sensor for the detection of toxic heavy metals. The sensor, consisting of an inductor, detection coil and interdigitated electrodes (IDE) in planar form, was fabricated using screen and gravure printing technologies on a flexible polyethylene-terephthalate (PET) substrate with silver based ink as metallization. The capability of the printed LC sensor for detecting very low concentrations of toxic heavy metals was demonstrated. The wireless response of the printed LC sensor revealed a very high sensitivity at picomolar levels of cadmium sulphide (CdS) and lead sulphide (PbS).

2012 IEEE Sensors, 2012

A novel fully printed flexible capacitive pressure sensor was fabricated using conventional scree... more A novel fully printed flexible capacitive pressure sensor was fabricated using conventional screen and gravure printing techniques. The sensor was successfully printed on a flexible polyethylene terephthalate (PET) substrate with silver (Ag) nanoparticle (NP) ink as the metallization layer and polydimethylsiloxane (PDMS) as the dielectric layer. The capacitive response of the sensor demonstrated a percentage change of 5 % and 40 % for minimum and maximum detectable compressive forces of 800 kPa and 18 MPa, respectively when compared to the base capacitance of 26 pF. At the minimum detectable pressure, the stability measurements resulted in a maximum variation of ± 0.15 % from the average capacitance value of 28 pf. The response of the printed device demonstrated the feasibility of employing traditional printing techniques for the fabrication of flexible pressure sensing devices.

A novel flexible strain gauge sensor was successfully screen printed on polyethylene terephthalat... more A novel flexible strain gauge sensor was successfully screen printed on polyethylene terephthalate (PET) substrate using silver (Ag) ink as metallization. The electro-mechanical characteristics of the printed strain gauge sensor were investigated by subjecting the sensor to a cyclic 3-point bend fatigue test. The sensors were subjected to an elongation of 1 mm and 2 mm, for 10,000 cycles at 0.5 Hz. Resistance changes of 0.64 % and 1.89 % were observed for the 1 mm and 2 mm elongations, respectively. An average increase of 9 % in the resistance was calculated for every 0.004 mm/mm increase in the strain, during a strain analysis test performed on the sensor. These responses of the fabricated sensor demonstrate its potential to be used in sensing applications for safety measures.

Sensors and Actuators B: Chemical, 2013

A novel electrochemical sensor was fabricated for the investigation of the effect of electron tra... more A novel electrochemical sensor was fabricated for the investigation of the effect of electron transfer between glutathione (GS) protected gold nanoparticles (AuNPs) and a new C 4 -thiol functionalized viologen axle molecule (V 2+ -SH) on pseudorotaxane formation. The sensor was fully screen printed with silver (Ag) ink on a flexible polyethylene terephthalate (PET) substrate. Square wave voltammetry (SQWV) based response of the sensor toward V 2+ -SH in the presence of Au 25 or 4 nm-Au demonstrated oneelectron transfer processes, based on 59 mV changes in peak potentials to more negative values. The response demonstrated the capability of the novel electrochemical sensor to be used for studying complex systems in volumes as small as 5-10 L, with less sample preparation time. and synthesis of novel metal-organic compounds and supramolecular architectures, with an emphasis on developing advanced materials for applications in nanotechnology, molecular machines, solar cells and anion extraction.

A novel surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated on a sil... more A novel surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated on a silicon (Si) wafer using a 400 nm inkjet printed thin film of silver (Ag) nanoparticle ink, with 150 nm particle size. The capability of the fabricated SERS substrate for detecting toxic heavy metals such as mercury sulfide (HgS), cadmium sulfide (CdS) and zinc oxide (ZnO) was demonstrated. The SERS based response of the printed substrate produced an enhanced Raman signal when compared to that of target molecules adsorbed on bare Si wafer. An amplification of the SERS intensity by an order of 3 to 5 times was observed for all test samples, due to the presence of hotspots between the metal nanoparticle aggregates. The responses demonstrated the feasibility of the novel SERS substrate to be used in applications for detection of toxic heavy metals.

2012 IEEE Sensors, 2012

ABSTRACT A novel flexible surface enhanced Raman spectroscopy (SERS) substrate was successfully f... more ABSTRACT A novel flexible surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated by gravure printing silver (Ag) nanoparticle ink, with ~20-50 nm particle size, as metallization on flexible polyethylene terephthalate (PET). The capability of the fabricated SERS substrate to be used as a sensor for detecting toxic heavy metal compounds such as mercury sulfide (HgS) was demonstrated. An enhancement factor of 5 orders of magnitude was obtained when compared to the intensity of Raman spectrum of target molecules adsorbed on bare PET. This response demonstrated the feasibility of the novel SERS substrate to be used in applications for detection of toxic heavy metals. In addition, the effect of temperature on the intensity of the Raman spectrum was also tested. The result showed 85 % decrease in intensity at 85 °C, when compared with the intensity at 25 °C.

Sensors and Actuators B: Chemical, 2012

A novel surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated on a sil... more A novel surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated on a silicon wafer using inkjet printing. Silver (Ag) nanoparticle (NP) based ink, with average particle size of 150 nm, was inkjet printed on the surface of the silicon wafer. A thickness of 400 nm was measured for the printed Ag NP film using vertical scanning interferometry. The Ag NP printed SERS substrate was tested toward heavy metal compounds like cadmium sulfide (CdS), zinc oxide (ZnO) and mercury sulfide (HgS). An amplification of the SERS intensity by an order of 3-5 times was observed for all test samples, due to the presence of hotspots between the metal nanoparticle aggregates. The responses demonstrated the feasibility of the novel SERS substrate to be used in applications for detection of heavy metal compounds. (A. Eshkeiti). pursuing the MS degree in Electrical Engineering at Western Michigan University, Kalamazoo. His research interests include design, fabrication, and characterization of printed sensor structures, strain gauge sensors, and lab-on-a-chip sensing systems.

A novel flexible surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated... more A novel flexible surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated by gravure printing a thin film of silver (Ag) nanoparticle ink with 20~50 nm particle size on polyethylene terephthalate (PET). The feasibility of the fabricated SERS substrate for detecting toxic heavy metals such as mercury sulfide (HgS) and cadmium sulfide (CdS) was demonstrated. The SERS based response of the printed substrate produced an enhanced Raman signal when compared to target molecules adsorbed on bare PET. An enhancement factor of 5 orders of magnitude due to existence of hot spots between nanoparticles was obtained. This response demonstrated the feasibility of the novel SERS substrate to be used in applications for detection of toxic heavy metals.

This paper reports on the successful development of a fully printed wireless LC sensor for the de... more This paper reports on the successful development of a fully printed wireless LC sensor for the detection of toxic heavy metals. The sensor, consisting of an inductor, detection coil and interdigitated electrodes (IDE) in planar form, was fabricated using screen and gravure printing technologies on a flexible polyethylene-terephthalate (PET) substrate with silver based ink as metallization. The capability of the printed LC sensor for detecting very low concentrations of toxic heavy metals was demonstrated. The wireless response of the printed LC sensor revealed a very high sensitivity at picomolar levels of cadmium sulphide (CdS) and lead sulphide (PbS).

2012 IEEE Sensors, 2012

A novel fully printed flexible capacitive pressure sensor was fabricated using conventional scree... more A novel fully printed flexible capacitive pressure sensor was fabricated using conventional screen and gravure printing techniques. The sensor was successfully printed on a flexible polyethylene terephthalate (PET) substrate with silver (Ag) nanoparticle (NP) ink as the metallization layer and polydimethylsiloxane (PDMS) as the dielectric layer. The capacitive response of the sensor demonstrated a percentage change of 5 % and 40 % for minimum and maximum detectable compressive forces of 800 kPa and 18 MPa, respectively when compared to the base capacitance of 26 pF. At the minimum detectable pressure, the stability measurements resulted in a maximum variation of ± 0.15 % from the average capacitance value of 28 pf. The response of the printed device demonstrated the feasibility of employing traditional printing techniques for the fabrication of flexible pressure sensing devices.

A novel flexible strain gauge sensor was successfully screen printed on polyethylene terephthalat... more A novel flexible strain gauge sensor was successfully screen printed on polyethylene terephthalate (PET) substrate using silver (Ag) ink as metallization. The electro-mechanical characteristics of the printed strain gauge sensor were investigated by subjecting the sensor to a cyclic 3-point bend fatigue test. The sensors were subjected to an elongation of 1 mm and 2 mm, for 10,000 cycles at 0.5 Hz. Resistance changes of 0.64 % and 1.89 % were observed for the 1 mm and 2 mm elongations, respectively. An average increase of 9 % in the resistance was calculated for every 0.004 mm/mm increase in the strain, during a strain analysis test performed on the sensor. These responses of the fabricated sensor demonstrate its potential to be used in sensing applications for safety measures.

Sensors and Actuators B: Chemical, 2013

A novel electrochemical sensor was fabricated for the investigation of the effect of electron tra... more A novel electrochemical sensor was fabricated for the investigation of the effect of electron transfer between glutathione (GS) protected gold nanoparticles (AuNPs) and a new C 4 -thiol functionalized viologen axle molecule (V 2+ -SH) on pseudorotaxane formation. The sensor was fully screen printed with silver (Ag) ink on a flexible polyethylene terephthalate (PET) substrate. Square wave voltammetry (SQWV) based response of the sensor toward V 2+ -SH in the presence of Au 25 or 4 nm-Au demonstrated oneelectron transfer processes, based on 59 mV changes in peak potentials to more negative values. The response demonstrated the capability of the novel electrochemical sensor to be used for studying complex systems in volumes as small as 5-10 L, with less sample preparation time. and synthesis of novel metal-organic compounds and supramolecular architectures, with an emphasis on developing advanced materials for applications in nanotechnology, molecular machines, solar cells and anion extraction.

A novel surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated on a sil... more A novel surface enhanced Raman spectroscopy (SERS) substrate was successfully fabricated on a silicon (Si) wafer using a 400 nm inkjet printed thin film of silver (Ag) nanoparticle ink, with 150 nm particle size. The capability of the fabricated SERS substrate for detecting toxic heavy metals such as mercury sulfide (HgS), cadmium sulfide (CdS) and zinc oxide (ZnO) was demonstrated. The SERS based response of the printed substrate produced an enhanced Raman signal when compared to that of target molecules adsorbed on bare Si wafer. An amplification of the SERS intensity by an order of 3 to 5 times was observed for all test samples, due to the presence of hotspots between the metal nanoparticle aggregates. The responses demonstrated the feasibility of the novel SERS substrate to be used in applications for detection of toxic heavy metals.