Mechatronics Systems Engineering, School of

Receive updates for this collection

Conductive Cellulose Composites with Low Percolation Threshold for 3D Printed Electronics

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2017-06-12
Abstract: 

We are reporting a 3D printable composite paste having strong thixotropic rheology. The composite has been designed and investigated with highly conductive silver nanowires. The optimized electrical percolation threshold from both simulation and experiment is shown from 0.7 vol. % of silver nanowires which is significantly lower than other composites using conductive nano-materials. Reliable conductivity of 1.19 × 102 S/cm has been achieved from the demonstrated 3D printable composite with 1.9 vol. % loading of silver nanowires. Utilizing the high conductivity of the printable composites, 3D printing of designed battery electrode pastes is demonstrated. Rheology study shows superior printability of the electrode pastes aided by the cellulose's strong thixotropic rheology. The designed anode, electrolyte, and cathode pastes are sequentially printed to form a three-layered lithium battery for the demonstration of a charging profile. This study opens opportunities of 3D printable conductive materials to create printed electronics with the next generation additive manufacturing process.

Document type: 
Article
File(s): 

A High-Performance Piezoelectric Vibration Sensor

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2016-12
Abstract: 

We are reporting on the design, fabrication, and characterization of wideband, piezoelectric vibration microsensors. Prototypes were fabricated in a commercial foundry process. The entire thickness of the handle wafer was employed to carve the proof-mass of the device, leading to high sensitivity at a reduced chip area. A thin layer of aluminum nitride was used for sensing the displacements of the proof-mass. A continuous membrane was employed for the device structure in order to push undesired modes to high frequencies. Sensors with different geometries were designed and fabricated. Analytic and finite element analyses were conducted to study device response. A lump element model was developed for the piezoelectric vibration sensor and used for the noise modeling of the complete sensor system. Various performance metrics for the devices were characterized experimentally. Fabricated prototypes exhibited sensitivities as high as 350 mV/g with first resonant frequencies of more than 10 kHz. These devices are particularly suited for emerging applications in high-frequency vibration sensing.

Document type: 
Article
File(s): 

Morphology of Electrospun Poly(ethylene oxide) Ultra-fine Fibres with Incorporated MoO3 Nanoparticles

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2016-12
Abstract: 

N-type semiconducting molybdenum trioxide (MoO3) nanoparticles embedded in polyethylene oxide (PEO) polymer ultra-fine fibres were deposited directly onto silicon substrates using an electrospinning technique. The effects of different MoO3/PEO concentrations as well as electrospinning parameters on the fibre morphologies were examined. Experimental results show that embedding nanoparticles and electrospinning onto small areas can be achieved without use of solvents or transfer of the deposited nanostructures. This approach offers a cost effective fabrication method to produce a diverse range of multifunctional materials for many applications including electronics, mechanical enhancement, drug delivery and gas sensing.

Document type: 
Article

Probing Mechanical Properties of Jurkat Cells under the Effect of ART Using Oscillating Optical Tweezers

Peer reviewed: 
Yes, item is peer reviewed.
Date created: 
2015
Abstract: 

Acute lymphoid leukemia is a common type of blood cancer and chemotherapy is the initial treatment of choice. Quantifying the effect of a chemotherapeutic drug at the cellular level plays an important role in the process of the treatment. In this study, an oscillating optical tweezer was employed to characterize the frequency-dependent mechanical properties of Jurkat cells exposed to the chemotherapeutic agent, artesunate (ART). A motion equation for a bead bound to a cell was applied to describe the mechanical characteristics of the cell cytoskeleton. By comparing between the modeling results and experimental results from the optical tweezer, the stiffness and viscosity of the Jurkat cells before and after the ART treatment were obtained. The results demonstrate a weak power-law dependency of cell stiffness with frequency. Furthermore, the stiffness and viscosity were increased after the treatment. Therefore, the cytoskeleton cell stiffness as the well as power-law coefficient can provide a useful insight into the chemo-mechanical relationship of drug treated cancer cells and may serve as another tool for evaluating therapeutic performance quantitatively.

Document type: 
Article
File(s):