Yang Bai1, Carl Meggs

1, Tim W Button

1,2

1 Metallurgy & Materials, University of Birmingham, Birmingham, United Kingdom 2 Central European Institute of Technology, Brno, Czech Republic

Introduction Having experienced more than 20 years’ research, Piezoelectric Energy Harvesting has shown to be a promising technology, and is predicted to approach commercialisation in several years. In order to evaluate the feasibility and explore potential applications, this poster presents the charging behaviour of vibration and wind energy harvesters based on integrated free-standing thick-film piezoelectric cantilevers, in which individual elements have been investigated and developed by the authors at earlier stages of the project.

Vibration Harvester - Individual Charging 1000 μF Capacitor - Individual

Contacts: YXB087@bham.ac.uk (Y. Bai); c.meggs@bham.ac.uk (C.Meggs); t.w.button@bham.ac.uk (T. W. Button)

Vibration Harvester - Array Charging 1000 μF Capacitor - Array

Figure 1. Proposed individual energy harvester with free-standing thick-film structure: (a) schematic of the construction; (b) the fabricated harvester.

~13 mm

~250 μm

0.1 g

Piezoelectric Thick-film

Piezoelectric Thick-film

Base (fixed end) Free end

Silver Lead Tip Mass

(a)

1 cm

(b)

Figure 2. (a) The schematic of the connection method (b) the picture of an array.

Table 1. Summary of the dimensions, tip masses and frequencies of the array.

Wind Harvester Based on Piezoelectrics

Figure 3. Pictures of wind harvester incorporating piezoelectrics: (a) front-side; (b) back-side

Free-spinning fan

(a) (b)

Diode bridge rectifiers

Individual harvesters

Magnets

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 25 50 75 100

Cap

acit

or

Vo

ltag

e (

V)

Time (min)

107Hz, 0.3g107Hz, 0.5g

2.1

1.3 V

olt

age

(V)

Time (ms) 20 80

3.6

2.8 Time (ms) 20 80

Vo

ltag

e (V

)

g≈9.8m/s2

107Hz, 0.3g

107Hz, 0.5g

Figure 4. Instantaneous output voltage and charging response of an individual harvester.

Test Sieve Shaker

0.0

0.5

1.0

1.5

2.0

100 105 110 115 120 125 130

0.5g

0.0

0.1

0.2

0.3

0.4

0 5 10 15 20

Summary • Vibration harvesters have been able to charge a 1000 μF capacitor,

under both harmonic and machinery vibration. • Proposed structure has also been proved feasible to incorporate to

a wind system, showing comparable output voltage and charging rate to those of the vibration systems.

Charging 1000 μF Capacitor - Wind

Figure 6. Instantaneous output voltage and charging response of a wind harvester in a series of four consecutive tests.

Array

Nano-voltmeter

Capacitor

Time (min)

Uc (V

)

Frequency (Hz)

Uo

(V)

Figure 5. (a) Test configuration, (b) harmonic output and (c) charging response of an array mounted on a sieve shaker.

Uo: RMS output voltage of the harvester

Uc: Capacitor voltage

(a) (b)

(c)

Laboratory fan used as wind source

4.0

2.8

Vo

ltag

e (V

)

20 80 Time (ms)

1 cm

1 cm

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0 5 10 15 20

Cap

acit

or

Vo

ltag

e (

V)

Test 1

Test 2

Test 3

Test 4

Time (min)

Consecutive