This document summarizes research on a human motion energy harvester for wearable applications. The harvester contains flat spiral-shaped coils and a neodymium magnet. When tested during walking at various speeds, it generated up to 14mW of power. Different shapes of embroidered inductors were also investigated. The harvester is small, lightweight and can be integrated into clothing without noticeable changes. It harnesses the natural motion of sleeves or garments to generate electricity from walking, making it a clean, mobile power source for wearable devices.

1. Human Motion Energy Harvester for Wearable Application
J.Blums 1, G.Terlecka 2, I.Gornevs 3, A.Vilumsone2
1TechnicalPhysics Institute, Riga Technical University, Riga, Latvia
2Textile Technology and Design Institute, Riga Technical University, Riga, Latvia
3Institute of Radioelectronics, Riga Technical University, Riga, Latvia
Contact: blum@latnet.lv
Main parts of the harvester inside the prototype Table I. Prototype in use – developed power
Mean power
Walking
Figure 1. Jacket with the Maximal (through 1 min
speed, km/h Steps in 1 min
electrical generator: power , mW of walking),
a - location of the flat mW
spiral shaped coils,
b - location of the 3 80 3 0,05
magnet, 4,5 103 14 0,11
c – set of flat coils,
d – permanent magnet 6 115 10 0,21
Human motion energy
harvester contains two
parts:
Design of flat inductors for energy harvesting:
 Set of flat, spiral-shaped coils consists of three groups of coils with identical Calculations show that generated energy depends on the shape of
winding direction, connected in series keeping 1 cm space between them.
the coil and the path of the magnet’s motion.
Each coil group consists of five layers of flat coils with a diameter of 25 mm
and the number of windings 50 placed one onto another with insulating
layer in between. Planar coils are made of copper wire (diameter 0.22 mm).
Embroidered inductors of different shape:
 The second generator part is lightweight, small and strong neodymium (Nd)
magnet with double magnetic field structure.
The volume of the generator (coils + magnet): about 4,8 cm3 and its mass 45 g. 1 2
Main properties:
 Due to flat, spiral-shaped inductive elements natural motions of sleeves are 3
used to move magnet along the coils instead of traditional «magnet inside a
coil» motion. Figure 3a. Embroidered inductors;
 The investigated generator can be used as a mobile and ecologically clean 1,2 and 3 – directions of the movement of the block-shaped
source of energy, easy in use and not substantially changing visual properties magnet;
of textile structures, its size or weight.
 Weight of the energy harvester is insignificant in relation to the weight of the 4
product and it provides the same easiness of motion as garments without 3
2
Channel A (mV)
installed energy generator. 1
0
 The generator with the flat coil does not need additional volume for magnet -1
-2
motion as it is located in a different part of garments, one of which is moved
-3
-4
340 360 380 400 420 440
against the other during the process of walking, and therefore can be Time (ms)
implemented almost in every garment.
Figure 3b. Corresponding voltage impulses, induced in outer turn of
Test of the prototype – walking with different speeds the inductor
The generator was tested by a wearer during the process of walking at different Conclusions
fixed speeds: 3, 4,5 and 6 km/h which corresponds to slow, normal and quick  Flat inductors for energy harvesting are under
walking of a middle-aged man.
investigation.
 The possibility to integrate human movement
energy electrodynamic converter with a flat
architecture into the clothes is proven.
 The insertion of the coils achieved without any
deformation of the coats of jacket; the position is
practically invisible from the right side of the
product.
Figure 2. Test of the prototype,  Embroidery technics are used to investigate the
the impulses of generated voltage and corresponding developed power. dependency of generated energy and developed
power on the geometrical shape of flat inductors.
Acknowledgments
The research is realised in the frames of European Social Fund co-financed project “Establishment of
interdisciplinary research groups for a new functional properties of smart textiles development and
integrating in innovative products" (ESF Nr 2009/0198/1DP/1.1.1.2.0./09/APIA/VIAA/148)
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