illumination security of white led in visible light
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2017 2nd International Conference on Artificial Intelligence: Techniques and Applications (AITA 2017) ISBN: 978-1-60595-491-2
Illumination Security of White LED in Visible Light Communication
Shu-yan REN*, Yan-qing SONG, Shi-gang CUI and Li ZHAO
Key Laboratory of Information Sensing & Intelligent Control, Tianjin University of Science and Technology, Tianjin, 300222, China
*Corresponding author
Keywords: Visible light communication, ELISA, RPE, Safety threshold.
Abstract. Medical experiments by white LED in visible light communication had been done to
explain influence on visual function. The isolated RPE cells were cultured and light source
illumination experiments with different illumination (lux), time and spectral range are designed.
Using ELISA, the intracellular transcription factors in each group were detected, which include
MCP-1 and IL-8. From experiments, the illumination safety threshold of white light is 500lux, and the
illuminance safety threshold of blue light is 300lux. Compared with illumination (lux), Spectral range
is the main factor of affecting visual function. In different spectral ranges, the magnitude of
illumination and the duration of irradiation also affect visual function.
Introduction
Compared with radio frequency wireless communication technology, the visible light
communication technology [1-2] based on white light LED has obvious advantages, which ensures
personal safety without electromagnetic radiation. It can be multiplexed with LED lighting devices to
achieve high bandwidth and high-speed optical communication access at low cost, which greatly
expanded the coverage of the network[3]. Therefore, the research on cooperative optimization of LED
lighting and communication parameters will supply a theoretical foundation for indoor applications of
visible light communication.
Through the basic medical experiments, the LED light source performance test and eye safety
assessment have been carried out. The isolated RPE cells were cultured[4-5], and different irradiation
experiments were carried out to obtain the response medical parameters. So a large number of
experimental data were provided for the visual safety evaluation[6]study. In the visible light office
communication demonstration system designed, signal transmitted by white LED light with different
illumination to obtain the communication rate, combined with the results of visual medical safety
experiments, to determine the communication parameters to conform to visual security of human and
provide reference data for the study of visible light communication.
Culture Experiments of RPE Cells
The retinal pigment epithelial cells (RPE) are shown in Figure 1, and the LED light source is arranged
at the top of the closed incubator without the interference of natural light. When illumination of LED
changes, the temperature of incubator is between 36.5℃ and 37.2℃. White LED light source is set to
1000lux, 500lux and 300lux, which continuously irradiate RPE cells for 6h, 12h and 24h respectively.
At the same time, the corresponding control group is also cultured with foil packs.
Figure 1. Culture experiments of RPE cells.
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RPE Cells Irradiation Experiments and Results Analysis
Experiments by Different Illumination and Time
The LED light source with different illumination and spectral range was used to irradiate the cells.
After the illumination was stopped, the general morphological changes of the cells were observed
under the invert microscope. MTT method was used to detect the proliferation of cells in each group
and control group, and the production of intracellular reactive oxygen species (ROS) in the light
group and control group was detected by DCFH-DA method.
RT-PCR is used to detect the expression of inflammatory factor MCP-1 and IL-8 mRNA. And
carried out the enzyme-linked immunosorbent assay (ELISA)[7] to detect the expression of
inflammatory factor MCP-1 and IL-8.
RPE cells irradiated by white LED with 1000lux and 500lux, and continuous irradiation keeps 24h,
the cells appeared obvious shrinkage, and shapes changed irregular, and cell connection is rare
(shown as Figure 2). After the intensity of 1000lux irradiated 12h, the size and morphology of cells
lost their typical polygon. After the intensity of 1000lux irradiated 6h, 500lux irradiated 12h, and the
intensity of 300lux irradiated 24h, cells were gradually circular, and polygonal shape is not typical.
But after the intensity of 300lux irradiated 12h, 500lux irradiated 6h and the intensity of 300lux
irradiated 6h, there was no obvious change in cells.
a) Intensity of 1000lux irradiated 24h b) Intensity of 500lux irradiated 24h
Figure 2. RPE cells irradiation experiments by LED light.
ELISA was used to detect the secretion of MCP-1 and IL-8 in RPE cells, and the supernatant of cell
culture was used to detect the secretion of MCP-1 and IL-8. Take the standard concentration standard
as the reference, curve was established. The 100ul sample was added to incubated for 2h at 37�,
followed by adding 100ul first antibody and 100ul enzyme labeled antibody and the 100ul substrate in
each hole, and incubated with the corresponding time. Finally 50ul termination liquid was added to
terminate the reaction.
1 2 3 4 5 6 7
200
210
220
230
EL
ISA
1 2 3 4 5 6 7
190
200
210
220
230
EL
ISA 不不时时时 1 2 3 4 5 6 7
180
190
200
210
220
EL
ISA
a) ELISA(IL-8)by 500lux white LED b) ELISA(IL-8)by 300lux blue LED c) ELISA(IL-8)by 500llux green LED
Figure 3. ELISA (IL-8) detection.
ELISA IL-8 concentration changes as shown in Figure 3. The coordinates of the 1 (first column) in
Figure3a is the concentration of IL-8 BOX with continuous 6h irradiation. Then each column denotes
extending the irradiation time of 3 hours in turn to detect IL-8 value, until the 7th column as the
irradiation time of 24 hours. From the figure, difference appeared in white light group with 500lux
illumination after 15 hours, but huge difference appeared 18 hours shown as the 5th column.
According to the Figure3b and 3c, obvious difference can been obtained in 300lux blue light group
after irradiation time of 12 hours. The experimental results show that the security threshold of white
light illumination is 500lux, and the blue light illumination safety threshold is 300lux. For the 500llux
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green group, 9 and 12 hours exposure data denote large individual differences, but the overall trend is
consistent although with some fluctuation in overall 1st~6th column data, and the 7th column at 21
hours irradiation shows a substantial difference between the values of ELISA.
1 2 3 4 5 6 7 8180
200
220
240
260
EL
ISA
1 2 3 4 5 6 7
190
200
210
220
230
240
EL
ISA
不不时时时 1 2 3 4 5 6 7 8180
200
220
240
260
EL
ISA
a) ELISA(IL-8)by 1000lux white LED b) ELISA(IL-8)by 500lux blue LED c) ELISA(IL-8)by 1000llux green LED
Figure 4. ELISA (IL-8) detection with changed parameters.
Similarly, the change of ELISAIL-8 concentration under high illumination is shown in figure 4.
Based on the above data, the cumulative threshold value of three different wavelengths of light based
on the change of ELISA IL-8 concentration index is obtained, as shown in table 1.
Table 1. The cumulative time limit of irradiation under different illumination.
White LED Green LED Blue LED
500lux 1000lux 500lux 1000lux 300lux 500lux
The
cumulative
time limit(h)
12 9 18 18 9 6
Meanwhile, ELISA was used to detect the secretion of MCP-1 in RPE cells to assist in the analysis
of the above experimental results, as shown in figures 5 and 6. And get the optimized time limit
threshold is shown in table 2.
1 2 3 4 5 6 7
48
50
52
54
56
MC
P-E
LIS
A
a) ELISA(MCP-1)by 500lux white LED b) ELISA(MCP-1)by 300lux blue LED c) ELISA(MCP-1)by 500lux green LED
Figure 5. ELISA (MCP-1) detection.
Table 2. The correct cumulative time limit of irradiation under different illumination.
White LED Green LED Blue LED
500lux 1000lux 500lux 1000lux 300lux 500lux
The
cumulative
time limit[h]
12 9 12 12 9 6
280
1 2 3 4 5 6 7 8
45
50
55
60
65
MC
P-E
LIS
A
a) ELISA (MCP-1) by 1000lux white LED b) ELISA (MCP-1) by 500lux blue LED
1 2 3 4 5 6 7
46
48
50
52
54
56
MC
P-E
LIS
A
c) ELISA (MCP-1) by 1000lux green LED
Figure 6. ELISA (MCP-1) detection with changed parameters.
Change the Spectral Section of the Light Source
Using three different spectral range of LED light source shown in Figure7 irradiated RPE cells, the
ELISA IL-8 concentration changed is shown in Figure 8. The 1st column, 2nd column and 3rd
denoted 500lux white light spectrum, 300lux blue spectrum and 500lux green spectrum respectively.
a) White light source spectrum b) Blue light spectrum c) Green light spectrum
Figure 7. Light source spectrum.
1 2 3
188
190
192
194
196
IL-E
LIS
A 不不不长长 1 2 3
180
185
190
195
200
205
IL-E
LIS
A
a) Irradiation for 6 hours with different spectrum b) Irradiation for 9 hours with different spectrum
1 2 3
195
200
205
210
IL-E
LIS
A
1 2 3
190
200
210
220
IL-E
LIS
A
c) Irradiation for 12 hours with different spectrum d) Irradiation for 15 hours with different spectrum
Figure 8. Comparison of IL-8 concentration under different spectral exposure.
281
RPE cells experiments by LED light irradiation with three different spectral range were conducted.
And RT-PCR, MCP-1 concentration changes are shown in Figure 9. The 1st column, 2nd column and
3rd denoted 500lux white light spectrum, 300lux blue spectrum and 500lux green spectrum respectively.
1 2 30.5
1
1.5
2
2.5
3
3.5
RT
-PC
R
1 2 3
0.6
0.7
0.8
0.9
1
RT
-PC
R
不不不长长 a) Irradiation for 6 hours with different spectrum b) Irradiation for 9 hours with different spectrum
Figure 9. Comparison of MCP-1 concentration under different spectral exposure.
Compared with two cases of white and green light at the same irradiation time, the concentration
change of IL-8 and MCP-1 is smaller, and LED with blue spectrum affected IL-8 and MCP-1
concentration of RPE cells in the same exposure time, which is prone to damage.
Conclusion
From above, based on basic medical experiments, the visual security of LED light source in visible
light communication has been studied. RPE cells were cultured in vitro and subjected to different
irradiation experiments. ELISA was used to detect the concentration of MCP-1 and IL-8 in RPE cells,
which are used to research the visual function with different illumination, different spectrum and
different irradiation time. Compared with the illumination, the spectral range is the main factor that
affects the visual function In different spectral range, the magnitude of illumination and the time of
illumination also affect the visual function.
Acknowledgement
This research was financially supported by National high technology research and development plan
(863 plan) (No. 2015AA033303) and Tianjin Natural Science Foundation (17JCQNJC12700,
15JCQNJC02400) and the National Natural Science Fund Project (No. 61503283)and the Research
and Development fund of TUTE (No. RC14-58, RC14-18, RC14-49, No. RC14-59).
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