Our recent work on H2S sensors have been highlighted at Nanowerk
n inkjet-printed, fully passive sensor capable of either humidity or gas sensing. The sensor is composed of an interdigitated electrode, a customized printable gas sensitive ink and a specialized dipole antenna for wireless sensing. The interdigitated electrode printed on
a paper substrate provides the base conductivity that varies during the sensing process. A fast response time of 3 min is achieved at room temperature for a H2S concentration of 10 ppm at a relative humidity (RH) of 45%. The passive wireless sensing is enabled through an antenna in which the inner loop takes care of conductivity changes in the 4–5 GHz band, whereas the outer-dipole arm
is used for chipless identification in the 2–3 GHz band.
More details can be found at:
Abdul Quddious , Munawar M. Khan , Farooq A. Tahir, Shuai Yang, Atif Shamim, Khaled N. Salama, Hammad M. Cheema, Disposable, Paper Based and Inkjet-Printed Humidity and H2S Gas Sensor for Passive Sensing Applications, Sensors 2016, 16, 2073; doi:10.3390/s16122073
The work has been accepted at IEEE transactions on circuits and systems.
H. Omran, Abdulaziz Alhoshany, H. Alahmadi, and K. N. Salama, A 33fJ/Step SAR Capacitance-to-Digital Converter Using a Chain of Inverter-Based Amplifiers" IEEE Transactions on Circuits and Systems I, 2016 10.1109/TCSI.2016.2608905
Its worth mentioning that a differential version of the work has been presented at the prestigious VLSI symposium with almost the same FoM due the use of Quasi-dynamic operation to maintain the energy efficiency for a scalable sample rate
H. Omran, A. Alhoshany, H. Alahmadi , and K. N. Salama, “A 35fJ/Step Differential Successive Approximation Capacitive Sensor Readout Circuit with Quasi-Dynamic Operation,” Symposia on VLSI Technology and Circuits, 2016.
This work builds on our earlier work:
on wireless energy harvesting from ambient RF signals. The dissertation is unique in developing an integrated RF-DC converter with on-chip antenna for lowering costs—in essence eliminating the cost of fabricating a different antenna. Another unique aspect of this thesis is the RF harvester’s integration with a wireless powered implantable sensor. Such sensors will become ubiquitous for medical applications, with their numbers reaching in the trillions. The need to power these sensors wirelessly eliminates batteries and makes the sensors maintenance free. Also, the achieved efficiencies of 65% at 433MHz with an input power of -15dBm is well in line with some of the best achieved efficiencies. Further, the developed RF-to-DC power converter, operating at 5.2GHz and incorporating adaptive self-biasing, is certainly unique. Even more, the peak efficiency of 90% is quite impressive. That is, this work carried out RF-to-DC harvesting at 400MHz and at 5.2GHz. This work was conducted in collaboration with Prof. Waleed Khalil, Thh ohio state university. The details are outlined in his thesis "Wide-Range Highly-Efficient Wireless Power Receivers for Biomedical Sensors".
Prof. John Volakis, the director of Electroscience lab, The ohio state university commented that " Mahmoud has done an impressive amount of work. His focus has certainly been on the integration of RF-to-DC wireless power harvester with medical sensors. Altogether, Mr. Ouda has published 5 journal papers in well-read and followed journals. This is impressive, and demonstrates the strong contributions of this dissertation."
His work resulted in following publications:
This CDC meets extremely low power requirements by using an operational transconductance amplifier (OTA) that is based on a current-starved inverter. It uses a charge-redistribution DAC that involves coarse-fine architecture. The prototype CDC was fabricated using a standard 180 nm CMOS technology. The 12-bit CDC has a measurement time of 42.5 μs, covers a wide range of capacitance of 16.14 pF with a 4.5 fF absolute resolution and consumes 3.54 μW and 0.29 μW from analog and digital supplies, respectively. For more details check
Abdulaziz Alhoshany, Hesham Omran, Khaled N. Salama, "A 45.8fJ/Step, Energy-Efficient, Differential SAR Capacitance-to-Digital Converter for Capacitive Pressure Sensing", Sensors & Actuators: A. Physical, Vol 245, Pages 10–18, 2016
This work builds on our earlier work:
Follow up work:
we report the fabrication of an advanced sensor for the detection of hydrogen sulfide (HS) at room temperature, using thin films of rare-earth metal (RE)-based metal–organic framework (MOF) with underlying topology. The sensor showed a remarkable detection sensitivity for HS at concentrations down to 100 ppb, with the lower detection limit around 5 ppb. The fum--MOF sensor exhibits a highly desirable detection selectivity towards HS vs. CH, NO, H, and CH as well as an outstanding HS sensing stability as compared to other reported MOFs. More details can be found at:
Omar Yassine, Osama Shekhah, Ayalew H. Assen, Youssef Belmabkhout, Khaled N. Salama and Mohamed Eddaoudi "H2S Sensors: Fumarate-Based fcu-MOF Thin Film Grown on a Capacitive Interdigitated Electrode" , Angew. Chem. Int. Ed.. doi:10.1002/anie.201608780
This builds on our earlier work with Eddaoudi's group:
resting work, PhD student Rawan Naous explores stochasticity in the cortex based on either the synaptic or neuronal components. The hardware emulation of these stochastic neural networks are currently being extensively studied using resistive memories or memristors. Aside from the size and area perspective, the impact on the system performance, in terms of accuracy, recognition rates, and learning, among these two approaches and where the memristor would fall into place are the main comparison points considered. For more details check:
Rawan Naous, Maruan AlShedivat, Emre Neftci, Gert Cauwenberghs and Khaled Nabil Salama, " Memristor-based neural networks: Synaptic versus neuronal stochasticity"AIP Advances 6, 111304 (2016); http://dx.doi.org/10.1063/1.4967352
This expands our earlier work:
The compatibility of the material to build microfluidic devices was evaluated in three different ways (1) determining if the UV cured resin inhibits the polymerase chain reaction (PCR) i.e., testing devices for PCR compatibility and (2) observing agglutination complex formed on the surface of the UV cured resin when anti-CRP antibodies and Creactive protein (CRP) proteins were allowed to agglutinate (3) by culturing human embryonic kidney cell line (HEK) cells and testing for its attachment and viability. This study finds importance in building Lab-on-chip/Micro Total analysis systems (µTAS) and organ-on-chip devices.
This work is a collaboration with prof. Niveen Khashab. This work was first presented at NEMS 2016 and was invited for a special issue at the IET Micro and Nano letter. More details can be found at
Shilpa Sivashankar, Sumeyra Agambayev, kholod alamoudi, Ulrich Buttner,Niveen Khashab, and Khaled Nabil Salama Compatibility analysis of 3D printer resin for biological applications, micro and nano letters, 2016
Shilpa Sivashankar, Sumeyra Agambayev, Ulrich Buttner, Khaled Nabil Salama, Characterization of Solid UV Curable 3D Printer Resins for Biological Applications, NEMS2016
Kaust is progressing in a very good way.
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