Triboelectric nanogenerators from reused plastic: An approach for vehicle security alarming and tire motion monitoring in rover

Highlights

• A vehicle security alert system and tire motion signaling and harvesting system are developed using a triboelectric nanogenerator (TENG).

• The TENG device is made by reusing the waste plastic bottle made of PET, which serves as the substrate for housing the triboelectric active layers.

• A Kapton layer is introduced at the bottom of the Ecoflex film as a charge accumulation layer.

• The device generates a maximum electrical output of voltage and current ~250 V and ~25 µA respectively.

Abstract

The fast urbanization and speedy growth of automobiles throughout the globe requires the development of a highly reliable vehicle security system to protect against vehicle crime. Similarly, the interest in space exploration increases rapidly in many of the countries, and the rover used in space exploration operates on solar power with 6 wheels for its movement. So, it is highly desirable to find an energy harvester as well as motion tracker in space exploration vehicles. Herein, a vehicle security alert system and tire motion signaling and harvesting system are developed using a triboelectric nanogenerator (TENG) with good reliability and cheap manufacturing cost. The TENG device is made by reusing the waste plastic bottle made of PET, which serves as the substrate for housing the triboelectric active layers. The active layers composed of sandpaper made roughness created PBAT (Polybutylene adipate terephthalate, commercially available as Ecoflex-0030) film as a negative layer, copper film as a positive layer, and electrodes. A Kapton layer is introduced at the bottom of the Ecoflex film as a charge accumulation layer. The entire layers with the reused plastic substrate made the device as an eye-shaped TENG device (EYE-TENG). The device generates a maximum electrical output of voltage and current ~250 V and ~25 µA respectively with a maximum instantaneous peak power density of ~16 µW/Cm². Furthermore, the device exhibits long term stability, durability and has potential to light up 100 LEDs. The device also demonstrates its capability is scavenging the biomechanical energy by hand and leg tapping at fast and slow motions. After that, the device was used to perform a vehicle security alarming system by placing into the vehicle tire and alarming with the help of an Arduino controller and Bluetooth module. The studies and results prove that the EYE-TENG is capable of acting as a sustainable power source as well as an alarming system and can be used as potential device in the future robotics, automobile industries, tire motion monitoring in rovers and aerospace electronics applications.

Introduction

The rapid growth of automobiles in the globe creates space for the development of waste mechanical energy due to the highly dense vehicle usage [1]. Many reports say that the vehicle population would increase rapidly and reaches billions in 2030 mainly from countries like India, China, and USA [2]. The waste mechanical energy from vehicle motion can be converted into useful electrical energy and been used for powering few of the automotive electronics systems. Similarly, the massive issue the society faces today is the development of a sustainable and eco-friendly power source. The continuous usage of fossil fuels creates tremendous changes in the environment, such as climate change, pollution, and global warming. Also, the regenerative capability of fossil fuels takes thousands of years. Similarly, the global plastic usage increases every year and a huge negative effect arises due to the plastic contamination on land, water and sea. The plastic contamination pollutes the land and spoils the growth of plants, spoils the ocean and damages the marine eco-systems. A report in 2010 indicates that more than 12 million metric tonnes of plastic wastes entering into the seas of the coastal countries [3]. Hence it is highly desired to develop a sustainable and clean energy source for the sustainable future and reducing the increasing energy demand. This leads to the development of significant challenges among scientists and researchers for the development of green energy sources. The law of conservation of energy says that the energy can neither be created nor destroyed but can be converted from one form to another. Mechanical energy is abundant in the earth ranging from water wave motions, vibrations, and human body motions, but this has not been highly utilized for the generation of electricity [4, 5]. The past few decades were using piezoelectric crystals, which generates electricity and been used commercially for small applications. In 2006, the first piezoelectric nanogenerator [6,7] was introduced for scavenging mechanical energy but limited to few drawbacks such as material cost, packaging, and less output. This issue was overcome by the invention of triboelectric nanogenerator (TENG) by Prof. Z. L. Wang, in 2012 [8], [9], [10]. The invention multiplies for scavenging waste mechanical energy and performing various self-powered applications by utilizing the real-time waste mechanical energy [11]. TENGs have more advantages such as less operating frequency, high power density, easy fabrication and less cost [12], [13], [14], [15]. These advantages gain more attention towards the TENG based energy harvesting [16,17]. So far TENGs have been used for scavenging energy from human body motions [18,19], muscular motions [20], vehicle motions [21], water wave motions [22], [23], [24], [25], [26], vibrations. Also, they have been used for various applications such as self-powered chemical sensors (glucose [27], pH [28], bio-molecule detections [29,30]), physical sensors [31] (acoustic sensors [32], pressure sensors [33,34], hand gesture sensors [35,36]) monitoring systems (pressure monitoring [1,5], location tracking [37,38], muscular monitoring [39], water quality analysis [30,40]). The IDTechEx prediction says that the triboelectric based transducers hold a market value of above 400 million dollars [41]. Similarly, with the increasing interest in space exploration and the present source for power is solar panel, which has drawbacks of weight and limited availability of sunlight source. To overcome that, TENGs can be introduced in the rover for energy harvesting from its tire motion. Also, with its movement and the generated electrical signal can be directly used for monitoring the motion of the rover. Recently TENGs have been reported for the use in Mars and tested its performance under laboratory conditions [42].

Herein, we present the most straightforward approach to design a recyclable eye-shaped triboelectric nanogenerator (EYE-TENG), which scavenges the waste mechanical energy from the rolling action of tires on the road. The fabricated device works on the contact and separation mode with a double-layer structure, which enhances the electrical output performance of the fabricated TENG device compared to a single layer device. The device consists of the copper film, which serves to be the positive layer, while the other layer comprises copper film and an irregular surface polymer, which is Ecoflex, and this serves to be a highly negative layer. Here we have introduced a Kapton film between the Ecoflex polymer and copper film. The substrate for this device is a discarded plastic bottle made of PET material, which is cut to make use as a part of the energy harvester. Since the materials used for making this device are recyclable, the device is entirely easy for fabrication and cost-effective. To investigate the energy harvesting performances of the EYE-TENG, several tests have been carried out such as voltage and current measurement with respect to different force, frequency and powering commercial electronic devices. The maximum output voltage and current obtained from the EYE-TENG devices are ~250 V and ~25µA respectively with a maximum power of ~225µW and an instantaneous peak power density of ~16 µW/Cm². Furthermore, the device exhibits long term stability, durability and real-time energy harvesting capability with the lit-up 100 LEDs. The device was further tested to demonstrate the real-time application of vehicle security alarming system by placing the EYE-TENG device inside the tire and connected with the programmable Arduino board. The generated electrical output upon the vehicle motion triggers the Arduino board and enables the Bluetooth module to send the alert warning to the mobile phone of the user. This approach paves way for the development of sustainable power sources as well as monitoring systems in the future automotive electronics industry.