Jeydmer Aristizabal

Electroactive Elastomeric Actuators for the Implementation of a Deformable Spherical Rover

This paper presents investigations toward the development of an inflated deformable rolling rover. The proposed novel locomotion system could find potential future use, for example, in scouting and exploration missions. The manufacturing procedure used to fabricate a preliminary prototype is presented in this paper. The prototype consists of a rigid frame and four dielectric elastomer actuator (DEA) sectors, which give the prototype a spherical shape. Analytical models are proposed to predict the electromechanical behavior of the DEA sectors and to estimate their effect on the prototypes dynamics. These models are validated through an experimental procedure.

Tungsten Lamps as an Affordable Light Source for Testing of Photovoltaic Cells

An improved Tungsten light source system for photovoltaic cell testing made from low-cost, commercially available materials is presented as an alternative to standard expensive testing equipment. In this work, spectral correction of the Tungsten light source is achieved by increasing the color temperature to ∼5200 K using inexpensive commercially available filters. Spectral measurements of the enhanced light source reveal that a better spectrum match towards the solar spectrum is achieved than what has been previously demonstrated. Specifically, the improved solar spectrum match is achieved by substantial filtering of the infrared range. The proposed setup is used to evaluate the performance of both silicon and organic based photovoltaic cells.

An Improved Light Source Using Filtered Tungsten Lamps as an Affordable Solar Simulator for Testing of Photovoltaic Cells

An improved Tungsten light source system for photo voltaic cell testing constructed from low-cost, commercially available materials is presented as an alternative to current high-cost solar simulators. In this work, spectral correction of the Tungsten light source is achieved by increasing the colour temperature to ~5200 K using inexpensive commercially available filters. Spectral measurements of the corrected light source reveal that a better spectrum match towards the solar spectrum is achieved than what has been previously demonstrated by our team. Specifically, the improved solar spectrum match is achieved by substantial filtering of the infrared range. The proposed setup is used to evaluate the performance of both silicon and organic based solar cells.

Method of fabricating a convenient light source and its evaluation in PV cell laboratory testing

This paper presents a simple method of fabricating a controlled light source for photovoltaic cell testing using commercially available materials, as a

Optimized organic photovoltaics with surface plasmons

In this work, a new approach for optimizing organic photovoltaics using nanostructure arrays exhibiting surface plasmons is presented. Periodic nanohole arrays were fabricated on gold- and silver-coated flexible substrates, and were thereafter used as light transmitting anodes for solar cells. Transmission measurements on the plasmonic thin film made of gold and silver revealed enhanced transmission at specific wavelengths matching those of the photoactive polymer layer. Compared to the indium tin oxide-based photovoltaic cells, the plasmonic solar cells showed overall improvements in efficiency up to 4.8-fold for gold and 5.1-fold for the silver, respectively.

Towards Self-Powering Touch/Flex-Sensitive OLED Systems

In this work, we present a novel design for an organic light-emitting system integrated with a mechanical energy harvesting and energy storage polymer films (patent pending). The system is configured into multiple stacked layers to form a thin, flexible, and lightweight assembly. The thin “film-like” device can be deformed and flexed to generate energy up to 0.5 mW within 100 s with ease. This platform technology finds applications in energy harvesting displays, electronic papers, key-input-pads, novel packaging, smart-IDs, disposable lab-on-a-chip optomicrofluidic systems, and much more. Results on the energy storage characteristics of the ionic polymer-metal composite film, the performance of a polyfluorene-based organic light-emitting device, and the mechanical energy transduction of the piezoelectric polymer energy harvester are presented. The polymeric nature of this platform system further makes it suitable for roll-to-roll print manufacturing, supporting applications requiring high volume and low cost.

Modelling approaches for a novel balloon-shape actuator made of electroactive polymers

The focus of this paper is on the characterization of a balloon-shape actuator (BSA), based on dielectric electroactive polymers, which has a spherical shape, and it is pre-strained by pressurized air. Under electrical activation, the electrodes on the inner and outer surfaces of the BSA squeeze the elastomer in its radial thickness direction which results in a radial expansion of the BSA. This actuator has the potential to display large deformations under high compression loads. In this paper, a finite element model of the BSA is created by using ANSYS11 software. The mechanical behaviour of the BSA is studied, and the simulation results are presented. The mechanical properties of dielectric elastomers are experimentally measured and hyperelastic models used to fit the experimental data.

Enhancement of indium-based organic photovoltaics

We report on the optimization of poly(3-hexylthiopene) and [6,6]-phenyl C61 butyric acid methyl ester bulk heterojunction photovoltaics using indium tin oxide anode and metallic indium cathode. The devices are fabricated, tested, and stored at ambient atmosphere, without encapsulation. By tuning the spin coating conditions for the hole-transport and the photoactive layers, along with a combination of mechanical pressure and annealing conditions during the cathode deposition, a 3-fold improvement is achieved, while maintaining devices stability. Consequently, the cells undergo a less than 10% loss in power conversion efficiency after 200 days.

2D and 3D integration with organic and silicon electronics

Organic electronics, such as OLEDs, OPVs, and polymer based power storage units (batteries and capacitors) are rapidly becoming low-cost viable alternatives to silicon-based devices. These organic devices however, are still reliant on the support functions of standard silicon components such as power and logic transistors. Integration of these organic devices with standard silicon electronics into a combined heterogeneous system requires specific design and fabrication considerations. Full-scale integration with conventional silicon based electronic components is challenging due to their incompatibility with common semiconductor fabrication process that can damage the active organic compounds. The printable/spray/spin nature of organic electronics fabrication makes 3D integration an attractive methodology. We propose to combine the organic and inorganic portions of a heterogeneous system by fabricating the modules separately (hence enabling parallel manufacturing) in a specific 2D layout scheme, and subsequently connecting the devices together in a post fabrication process. In this paper we discuss the 2D designs in detail and propose a 2D-3D hybrid design as well as a fully 3D stacked design for organic electronics with energy storage devices in a face-to-back configuration. The fabrication process of each device and the integration of OPVs and OLEDs with power storage devices are discussed. An overview of test procedure and fault tolerances for the proposed configuration is provided. Finally, a potential solution for a new test environment derived from a mixed configuration of different technologies and materials is proposed.