Hariyanto Gunawan

A New Approach of Polyvinylidene Fluoride (PVDF) Poling Method for Higher Electric Response

Good response, in particular high sensitivity, of polyvinylidene fluoride (PVDF) attracts a lot of research works on its manufacturing process and applications. Polarization is an important factor that is influential to the performance of PVDF. In this article, a new polarization method using ITO (Indium Tin Oxide) glass is proposed. Different from the conventional poling method using metal eletrode coated onto PVDF film, ITO glass is used as electrode to transmit the electric field voltage into PVDF film for poling. With the advantage of applying higher electric field in the process of polarization and eliminating the occurrence of flashover and arcing efficiently, this approach can thus make PVDF film gain better electric output response. Also, thinner film is constructed would be another advantage of sensitivity improvement. Comparison with conventional method for regular polarization area is carried out by using both FTIR and DSC equipment. Piezoelectric charge constant d33 and electricity output response as well as sensitivity of PVDF are measured in experiment, which indicate ITO glass poling method is superior to conventional technique.

Analysis and design of roof turbine ventilator for wind energy harvest

Harvesting energy using roof turbine ventilator and electroactive material has been investigated to verify its performance. Since electric power gained from a single piece of regular size is usually small, auxiliary device to vibrate multiple pieces of electroactive materials in order to harvest more power is required. In this paper, an attempt of using the developed nozzle wind collector associated with the popular roof turbine ventilator employed with gear mechanism to impact and vibrate a group of electroactive material to generate electricity is proposed. Number of blade and blade angle of the roof turbine ventilator are influential to the effectiveness of wind collection. Also, number of electroactive material employed on the turbine ventilator under the wind speed in environment eventually determines the efficiency of wind harvest. A simple model is derived to estimate the minimum driving force from the wind power that needs to overcome the inertia of the turbine ventilator mechanism and the electromechanical energy conversion of electroactive materials. Wind drag force is calculated by using CFD is assumed to provide such driving force. Various combinations of the blade angle, number of blade and electroactive material actuators are investigated in simulations. Optimum design concerning the environment wind resource and configuration of turbine ventilator is discussed. According to several case studies, a few of design trends is addressed for better efficiency of energy harvest. Since multiple electroactive materials are employed, circuitry design with parallel input sources is implemented to sum up the current and integrate the power.

A New Approach for Surface Poling of Polyvinylidene Fluoride (PVDF)

PVDF has been popularly used for miscellaneous sensor and energy harvesting purposes. The advantages of flexible and light characteristics in particular enhance more interest. A new approach of using ITO glass for surface poling is investigated in this study. Instead of using metal electrode onto the PVDF surface, ITO is coated onto glass for conducting electrode. It can provide an easy way of electrode pattern design. Also, higher electric field can be applied in the process of poling so that higher response is achieved. Properties of PVDF films are characterized by using d31 meter to measure the piezoelectric constant and using Fourier Transformed Infrared Spectroscopy (FTIR) and Differential Scanning Calorimeter (DSC) to measure β-crystallization. From the experiment results, it indicates that PVDF film makes use of the ITO glass poling method will gain higher output voltage and current as compared to traditional poling technique. Comb type electrode pattern, for example, is efficient to generate higher output response for planar polarization and is able to control the desired output voltage and current. Using a whole piece of ITO glass for poling with pattern design can avoid from the defect of non-uniform polarization at the corners that usually happens in using metal electrode. Compared to the PVDF embedded in a cantilever and a pressing structure, the latter one will gain more output response.

Experimental investigation of electrode pattern design for PVDF response

Polyvinylidene fluoride (PVDF) films widely used in many applications is due to its flexibility, good response and sensitivity. Electrode pattern is one of the primary factors that are influential to the performance of PVDF films. Different design of electrode pattern influences output response of PVDF. In addition, structure system which demonstrates input energy and output response has correlation with electrode pattern design. In this article, three types of PVDF films including unimorph, stack, and zig - zag, are investigated and compared. Bending moment imposing to a cantilever structure and force directly pressing onto the PVDF films structure are both concerned in experiment. From experimental results, both d33 and d31 piezoelectric charge constants show simultaneous response in consequence of a force applied onto PVDF films. Furthermore, d31 response is larger than d33 for both structures, which indicates d31 constant contributes more response in PVDF films. This phenomenon is useful to define kind of structure system so that optimum response of PVDF films can be achieved.

Circuitry design for direct wind energy harvest system

A wind energy harvest system by using piezoelectric polyvinylidene fluoride (PVDF) is proposed and investigated in this research. Nozzle accelerator is designed to collect wind from environment and increase wind velocity. Using the wind induced drag force to directly blow and vibrate the PVDF employed on the subsequent duct is a simple structure of generating electricity by means of piezoelectric direct effect. Battery-support pull-up circuitry is designed to harvest very small amount of electricity from PVDF.

Design of direct and indirect wind energy harvest systems

Developing wind energy by using wind collector and electroactive materials are proposed and investigated in this article. Two systems will be considered to harvest energy: direct and indirect system. In direct system, wind induced drag force directly blow and vibrate the electroactive materials in the duct for generating electricity. Wind flow-guided mechanism is designed to collect arbitrarily blowing wind in environment and guide the flow direction perpendicular to the cross section of the nozzle as much as possible so that more uniform velocity distribution profile is achieved. Nozzle accelerator is designed for the purpose of increasing wind velocity. Indirect system uses gear as additional mechanism to impact and vibrate the electroactive materials. Two types of indirect system integrating the wind collector with fan and roof turbine ventilator to impact and vibrate electroactive materials are proposed.