Generation of electricity

“GENERATION OF ELECTRICITY FROM HUMANS USING NANO ROBOTS”

“GENERATION OF ELECTRICITY FROM HUMANS USING NANO ROBOTS”

ABSTRACT:

The idea is to generate electric energy from the mechanical movements of living beings. When living beings make mechanical movements, they spend their energy some of which is converted to work. The wasted energy can be converted to electrical energy with the help of nanogenerators. The nano generators have a piezo electric crystal (say ZnO) which is made up of nanoparticles. These piezo electric crystals can be placed inside the sole of shoes. When the person walks, pressure is applied on the piezoelectric crystal. When force is applied on a piezo electric crystal (or nano wires), it results in displacement of the charge on its face .This unbalances the charges and creates an electric field that produces a current when the nanowire is connected to a circuit. Each Piezo electric nano wire can produce maximum of 50mv spike. Array of nano wires can be used to produce considerable amount of power. The produced power can be used to power cell phones or some medical equipment, which a person may carry with him. By using this on animals, it can be used to power critter cam’s which allows us to observe the animal neck to neck for a longer time than battery powered critter cam. This could be beneficial to soldiers in the field, who now depend on batteries to power their electrical equipment. As long as the soldiers were moving, they

could generate electricity

INTRODUCTION:-

When you walk, you generate 67 watts of power. Your finger movement is 0.1 watt. Your breathing is one watt. If you can convert a fraction of that, you can power a device. From the concept we've demonstrated, we can convert 17-30 percent of energy is converted to useful energy. Their results confirm a theory: zinc oxide nanowires will show a powerful piezoelectric effect, which is the production of electricity in response to mechanical pressure.

NANOTECHNOLOGY:-

Nanotechnology is the science of creating or modifying materials at the atomic and molecular level to develop new or enhanced materials and products. The breakthroughs are based on work with nanometers - each one billionth of a meter in size - about one ten-thousandth the diameter of a human hair, or a thousand times smaller than a red blood cell. By converting mechanical energy from body movement, muscle stretching or water flow into electricity, these nanogenerators" could make possible a new class of self-powered implantable medical devices, sensors and portable electronics.

PIEZOELECTRIC DEVICE (ZnO):-

Piezo electric, thermoelectric and pyroelectric transducers are used to generate the electrical Energy produced by chemical process, mechanical process or thermal process. ZnO is a typical piezoelectric inorganic semiconducting material used for electromechanical and thermo electrical energy conversion. Nanostructures of ZnO,[such as nanowires (NWs),nanobelts (NBs) nanotubes, nanorings, nanosprings, and nanohelices, While most of the current applications focus on its semiconducting Properties, only a few efforts have utilized the nanometerscale Piezoelectric properties of ZnO. Using ZnO NW arrays grown on a single-crystal sapphire substrate we have successfully transformed mechanical energy into electrical energy at the nanoscale.

PRINCIPLE:-

A conductive atomic force microscopy (AFM) tip was used in contact mode to deflect the alignedNWs. The coupling of piezoelectric and semiconducting properties in ZnO creates a strain field and charge separation across the NWs as a result of their bending. Bending of NW is obtain here by mechanical movement of humans .The rectifying characteristic of the Schottky barrier formed between the Metal tip and the NW leads to electrical current generation. This is the principle behind piezoelectric nanogenerators.

SELECTIONOF SUBSTRATE OF ZnO:-

(Growing of ZnO in plastic substrate)

The ceramic and semiconducting substrates used for growing ZnO NWs are hard and brittle and cannot be used in applications that require a foldable or flexible power source, such as implantable biosensors. In this Communication, by Using ZnO NW arrays grown on a flexible plastic substrate, we demonstrate the first successful flexible power source built on conducting-polymer films. This approach has two specific Advantages: it uses a cost-effective, large-scale, wet-chemistry Strategy to grow ZnO NW arrays at temperatures lower than 80 °C, and the growth of aligned ZnO NW arrays can occur on a large assortment of flexible plastic substrates. The latter advantage could play an important role in the flexible and portable electronics industry. Various dimensions, shapes, and orientations of

ZnO NWs and micro wires on flexible plastic substrates have been shown to be capable of producing piezoelectric voltage output, giving a real advantage for energy harvesting using large-scale ZnO NW arrays. The voltage generated from a single NW can be as high as 50 mV, which is large enough to power many nanoscale devices. The ZnO NWs were grown in solution using a synthetic chemistry approach. Figure 1 shows a series of scanning electronmicroscopy (SEM) and transmission electron microscopy (TEM) images of typical ZnO NW arrays grown on a conductive Plastic substrate. Figure 1a shows a low-resolution, top down view of the densely aligned NW arrays. The alignedNWs have a uniform diameter of 200–300 nm and a hexagonal cross section, as indicated by the magnified SEM image in Figure 1b. The SEM image in Figure 1c displays ZnO NWs ca. 2 lm long aligned perpendicular to the plastic substrate.

POWER GENERATION: INAVATIVE APPROACH:

(Structure of Power generating device using ZnO) It is worth noting that by controlling reaction conditions such as temperature, concentration, pH value, reaction time, and plastic-substrate surface quality, NWs of different density distributions, dimensionality, and alignment have been fabricated for electrical measurements. The NWs have a density of ca. 1 lm–2 on a Au-coated plastic substrate. The NWs are typically 100–350 nm wide and ca. 1 µmlong. Figure 2a is a schematic depicting the experimental setup used for measuring the mechanical introduced piezo electric is charge from individual NWs. A conductive Si tip coated with a Pt film with a cone angle of 70° was used for AFM measurements. The rectangular cantilever had a calibrated normal spring constant of 1.857 Nm–1. In the AFM contact mode, a constant normal force of 5 nN was maintained between the tip and sample surface. When the tip was scanned over the top of the ZnO NWs, the tip height was adjusted according to the surface morphology and local contacting force. For the electric contact at the bottom of the NWs, Ag paste was applied to connect the Au film on the plastic substrate surface to the measurement circuit. Connecting Ag and ZnO produce an Ohmic contact. The output voltage across an external load of resistance RL= 500 MX was continuously monitored as the tip was scanned over the NWs. In contact mode, as the tip was scanned over the vertically aligned NWs, the NWs were bent consecutively. The tip forced the elastic

Deflection of the oriented ZnO NWs and produced a charge separation and a voltage drop across the diameter of the NWs, with the stretched and compressed sides having positive and negative piezoelectric potentials, respectively. The center axis of the NW, as indicated by the dotted line, remained neutral. As the conductive tip was scanned across the neutral axis, a discharge occurred when the tip touched the compressed side of the NW. A single NW that has a diameter of 300 nm can produce an output voltage discharge of ca. 45 mV (Fig. 2b),

Which is the voltage drop across an external resistor converted using the measured electrical current.

CALCULATION BEHIND THIS APPROACH:-

The true output voltage should be higher if we consider the inner resistance of the NW. Figure 2b is a typical voltage output for an AFM tip scanning over a single NW. Because of the limited scan speed of the AFM tip in comparison to the discharge time, only two data points were captured around the peak area, which suggests that the true peak could be twice as large as the measured 45 mV shown in this profile. Therefore, the lifetime decay constant of the circuit shown in Figure 2a is estimated to be sc = 4.4 ms, based on the equation

Sc = (RL +Rnw) Cnw

Where RL and Rnw are the resistances for the external load (500 MX) and the ZnO NW, respectively, and Cnw is the capacitance of the NW and the measurement system. As previously reported,Rnw is negligible in comparison to the external load; thus, the capacitance of the NW can be calculated by Cnw ≈ sc/RL.

The output piezoelectric energy, Wo, for a single pulse is

Wo = 1/2CnwVp2 = scVp

2/2RL = 8.9 × 10–15 J, where Vp is the peak voltage. Here Wo only represents the harvested electrical energy from the first half cycle of the NW resonance that results from a single touch of the tip to the NW.

Power was calculated based on the average energy generated within the resonance lifetime, and it was assumed that the energy generated for half of the resonance cycles was collected. In this case, the individual NWs are typically 300 nm in diameter, exhibit a hexagonal cross section, and are ca. 1 lm in length. According to mechanical vibration theory,

COMMUNI

EXPERIMENTAL OUTPUT:-

The output power of a single NW is 10–20 pW. Figure 2c is a 3D plot of a topographic AFM Scan of a 40 µm×40 µm area of the ZnO NW array. The scanning direction is from the front to the back,

Which can be seen from the raised linear traces on the flexible plastic substrate? Because of the flexibility of the plastic substrate and in spite of the firm adhesion to the Ag paste, the substrate surface profile under tip contact was somewhat wavy. Relative to the plastic substrate, the NW array was revealed to have a height distribution of 0.5–2.0 µm. The corresponding 3D plot of the voltage output image is shown in Figure 2d. There are a number of sharp peaks ranging from 15 to 25 mV that represent voltage outputs. By counting the pulse numbers shown here with respect to the number of NWs in the topography profile in Figure 2d, the ratio of voltage peaks to the

number of available NWs is 90:150 or about 60 %, which suggests that the discharge events of the NWs captured by the AFM tip correspond to at least 50% of the NWs. In fact, because of the limitation

In the data-collecting speed of the atomic force microscope, which has a data step size of ca. 156.2 nm in this measurement?

Figure 2(d) The discharge peaks of some NWs were missed, possibly due to Figure 2(d) poor contact between the tip and the NWs and/or due to multiple contacts with neighboring NWs. It is suggested that both suitable bonding strength between the ZnO NWs and the polymer substrate and a uniform density distribution of NWs in the array might be very important in terms of improving the piezoelectric discharge efficiency. These two issues, together with Figure 2(d) the power output calculations, To calculate the total number of NWs that effectively produced electrical energy output, we assumed an average voltage peak height of 20 mV and the density of ZnO NWs on the plastic substrate was very conservatively estimated to be 1 µm–2. The power density per unit substrate area is ca. 1–2 pWµm–2, that is, 0.1–0.2 mWcm–2, which is large enough to power a variety of devices that operate at lower power consumption, such as microelectro mechanical systems (MEMS), nano electromechanical systems (NEMS), and other nanoscale devices.

ANALYSIS OF OUTPUT:

The voltage-output peak begins to increase when the AFM tip touches the flat cross section of the NW, and the voltage peak reaches its maximum when the AFM tip reaches the side edge of the top flat cross section of the NW. When the AFM tip starts to cross the central axial line of the NW,the voltage discharge begins, which occurs between two data points corresponding to the center of the discharge peak. When the tip completely releases the NW tip, the discharge is determined by the characteristics of the external circuit. The delay in the voltage peak in reference to the topography profile is entirely consistent with the mechanism presented previously. The inset in Figure 3 displays the 2D AFM topography image and the corresponding voltage/current output image recorded simultaneously when the AFM tip scans over a 6.5 µm× 3.2 µm areas. The height profile in the top image indicates that the local density of the NWs is so large that the AFM tip could not resolve them individually because of the tip size effect; thus, only the surrounding NW edges could be resolved. The corresponding voltage-output profile reveals that the red dots are distributed only at the extreme right-hand side, indicating that the discharge occurs at the end of the tip scan over the NWs. In this case, the high local density of the NW array prevented the deflection event from achieving Completion without multiple contacts. Therefore, a reasonable NW density distribution that matches with the tip size and scanning speed would be necessary for improving the voltage-output number. we found that a single NW generated ca. 0.5 pWat 10 mVof electrical power using AFM tip deflection at a 5 nN contact force. Here, NWs grown on a polymer substrate with diameters of 300 nm and lengths of 1 µm give rise to an output power of ca. 5 pWat 45 mV. This value has improved by an order of magnitude.

TO EVALUATE THE POWER-GENERATING CAPABILITY

The small normal tip force (5 nN) may not be sufficiently strong to deflect the ZnO micro wires. To find out why only a

few peaks were detected in the AFM scan

few peaks were detected in the AFM scan

array were pushed down by the AFM tip, Several possible reasons may account for this result.

1. The adhesion between the Au-coated base and the ZnO micro wires could be so weak that it cannot bear the force applied by the AFM tip.

2. Finally, the density of the wires could be so high that there is not much room for the wires to be deflected by the AFM tip without touching neighboring wires; thus, the piezoelectric current, if any, may slowly leak out, resulting in a gradual discharge signal.

We must improve bonding between the NWs and connecters (Ag coating & Pt tip)

ELECTRICAL MEASUREMENT:

Electrical measurements on the aligned NW array were conducted using an atomic force microscope (Molecular Force Probe MFP-3). The detailed methodology for generating electricity using a conductive AFM tip was reported previously,

SUMMARY

In fourth coming year nanotechnology will occupy the nook and corner of science and technology. The nanodevices require low power and the power produced using humans is sufficient for driving them. Thus power produced is free of cost and will be quite useful for soldiers.