Energy Scavenging

A Look at Nano-fibers and Other Piezoelectric Devices for

Body Area Networks

Presented by Stuart Wooters

Outline

• Characteristics of Movement Scavenged Energy

• Nano-Fibers• PVDF• Potential Implementations• Design considerations

Characteristics:

• What are some of the requirements of movement generated energy?– Frequency Range– Types of Movement– Energy Potentials

Microfibre–nanowire hybrid structure for energy scavenging

Yong Qin1, Xudong Wang1 & Zhong Lin Wang1

Basic Concept

• Use vibrations and friction between two fibers to create an electric current.

• Textile fibers are dense and have the potential of accumulating a lot of energy.

Yong Qin , Xudong Wang & Zhong Lin Wang "Microfibre-nanowire hybrid structure for energy scavenging", Nature, Volume 451, 14 February 2008 Page(s): 809 - 814.

Structure

• Fibers are coated in a Zinc Oxide growth.

Yong Qin , Xudong Wang & Zhong Lin Wang "Microfibre-nanowire hybrid structure for energy scavenging", Nature, Volume 451, 14 February 2008 Page(s): 809 - 814.

Conceptual Analogue

Yong Qin , Xudong Wang & Zhong Lin Wang "Microfibre-nanowire hybrid structure for energy scavenging", Nature, Volume 451, 14 February 2008 Page(s): 809 - 814.

IV Curve of Coated Strand

Yong Qin , Xudong Wang & Zhong Lin Wang "Microfibre-nanowire hybrid structure for energy scavenging", Nature, Volume 451, 14 February 2008 Page(s): 809 - 814. (Supplement Figure 1)

IV Curve of Bent Strands

Yong Qin , Xudong Wang & Zhong Lin Wang "Microfibre-nanowire hybrid structure for energy scavenging", Nature, Volume 451, 14 February 2008 Page(s): 809 - 814. (Supplement Figure 2)

Diode characteristics help insure same direction current for all nano-fibers

Short Circuit and Open Circuit Measurements at 80rmp

Yong Qin , Xudong Wang & Zhong Lin Wang "Microfibre-nanowire hybrid structure for energy scavenging", Nature, Volume 451, 14 February 2008 Page(s): 809 - 814.

Range of Frequencies

Yong Qin , Xudong Wang & Zhong Lin Wang "Microfibre-nanowire hybrid structure for energy scavenging", Nature, Volume 451, 14 February 2008 Page(s): 809 - 814. (Supplement Figure 6)

Six Fibers

Yong Qin , Xudong Wang & Zhong Lin Wang "Microfibre-nanowire hybrid structure for energy scavenging", Nature, Volume 451, 14 February 2008 Page(s): 809 - 814. (Figure 4)

Viability Case 1 (Cylindrical Fibers)

P=4nA x 3mV / .2s = 60pW

Effective Power:19 mW per 1m2

Yong Qin , Xudong Wang & Zhong Lin Wang "Microfibre-nanowire hybrid structure for energy scavenging", Nature, Volume 451, 14 February 2008 Page(s): 809 - 814. (Supplement)

Viability Case 2 (Square Fibers)

Yong Qin , Xudong Wang & Zhong Lin Wang "Microfibre-nanowire hybrid structure for energy scavenging", Nature, Volume 451, 14 February 2008 Page(s): 809 - 814. (Supplement)

P=4nA x 3mV / .2s = 60pW

Effective Power:76 mW per 1m2

Energy Generation using Piezo Film

R H Brown, Atochem Sensors Ltd, 1991

Basic Equations

• Charge Density:D = Q/A = d3nXn

• Open Circuit VoltageV0 = g3nXnt

R H Brown “Energy Generation using Piezo Film” published by Measurment Specialties original publish year 1991

Energy Expectations

• Maximum Charge Density:– 7mC/m2

• Maximum Energy Expected:– 200 kJ/m3

R H Brown “Energy Generation using Piezo Film” published by Measurment Specialties original publish year 1991

PVDF (Polyvinylidene Fluoride)

• Generates energy through stress/strain

• Kinetic Energy to Electrical Energy– Dropping Ball test– Stepping test

R H Brown “Energy Generation using Piezo Film” published by Measurment Specialties original publish year 1991

Basic Measurements

R H Brown “Energy Generation using Piezo Film” published by Measurment Specialties original publish year 1991

Potential Implementations

• How can we incorporate these devices into our networks?

• Can they be more than good sensors?

Design Considerations

• What do you do when your not scavenging energy?

• How do you retain your energy?• How would you control different

energy modalities?