Muhammad Omar Shaikh

Immunosensor for the ultrasensitive and quantitative detection of bladder cancer in point of care testing.

An ultrasensitive and real-time impedance based immunosensor has been fabricated for the quantitative detection of Galectin-1 (Gal-1) protein, a biomarker for the onset of multiple oncological conditions, especially bladder cancer. The chip consists of a gold annular interdigitated microelectrode array (3×3 format with a sensing area of 200µm) patterned using standard microfabrication processes, with the ability to electrically address each electrode individually. To improve sensitivity and immobilization efficiency, we have utilized nanoprobes (Gal-1 antibodies conjugated to alumina nanoparticles through silane modification) that are trapped on the microelectrode surface using programmable dielectrophoretic manipulations. The limit of detection of the immunosensor for Gal-1 protein is 0.0078mg/ml of T24 (Grade III) cell lysate in phosphate buffered saline, artificial urine and human urine samples. The normalized impedance variations show a linear dependence on the concentration of cell lysate present while specificity is demonstrated by comparing the immunosensor response for two different grades of bladder cancer cell lysates. We have also designed a portable impedance analyzing device to connect the immunosensor for regular checkup in point of care testing with the ability to transfer data over the internet using a personal computer. We believe that this diagnostic system would allow for improved public health monitoring and aid in early cancer diagnosis.

A Room Temperature H2 Sensor Fabricated Using High Performance Pt-Loaded SnO2 Nanoparticles

Highly sensitive H2 gas sensors were prepared using pure and Pt-loaded SnO2 nanoparticles. Thick film sensors (~35 μm) were fabricated that showed a highly porous interconnected structure made of high density small grained nanoparticles. Using Pt as catalyst improved sensor response and reduced the operating temperature for achieving high sensitivity because of the negative temperature coefficient observed in Pt-loaded SnO2. The highest sensor response to 1000 ppm H2 was 10,500 at room temperature with a response time of 20 s. The morphology of the SnO2 nanoparticles, the surface loading concentration and dispersion of the Pt catalyst and the microstructure of the sensing layer all play a key role in the development of an effective gas sensing device.

Real-Time Monitoring via Patch-Type Piezoelectric Force Sensors for Internet of Things Based Logistics

We propose the use of simple and low cost piezoelectric patch type force sensors for logistic applications to ensure safety of the package while also detecting damage suffered. The sensors are connected to a prototype readout system that can record the data and transfer it wirelessly via a Bluetooth module. The data can be received by an in-vehicle telematics device which can upload it directly to the cloud database, thus allowing real time monitoring of package condition during transportation. This logistics management model would aid in improving the quality of services provided by the logistics company while also earning consumer credibility. Thus, we believe that these patch type force sensors can be realistically implemented in logistics in the near future.

Ultrasonic tactile sensor integrated with TFT array for contact force measurements

In this study, we propose an ultrasonic tactile sensor for real time contact force measurements and high-resolution shape recognition to enable safe and reliable robotic grasping of objects that may vary in compliance or texture. The sensing mechanism utilizes piezoelectric transduction where an AC signal is applied to a polyvinylidene fluoride (PVDF) thin film to generate pulses of ultrasound waves that travel upwards through the sensor components to the contact interface while a receiver PVDF thin film detects the reflected waves and produces a localized voltage output that is detected by the TFT (Thin-Film Transistor) array layer. The ability of the tactile sensor to detect contact forces can be attributed to the sensor surface having a thin compliant PDMS layer with a microstructure array. When the sensor contacts objects, the microstructures act as force concentrators, resulting in the localized deformation of the PDMS layer and an observed linear response to normal static forces in the range of 1 to 6 N. The TFT array output after signal processing produces a two-dimensional grayscale image that enables not only high-resolution imaging but also contact force information for improved robotic grasping performance.