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Programmable and low-cost ultraviolet room disinfection
device
Marcel Bentancor
⇑
, Sabina Vidal
Laboratorio de Biología Molecular Vegetal, Facultad de Ciencias, Universidad de la Republica, Iguá 4225, Montevideo, Uruguay
article info
Article history:
Received 2 June 2018
Received in revised form 19 October 2018
Accepted 30 October 2018
Keywords:
Disinfecting
Ultraviolet
Sterilizer
abstract
Here is presented a room disinfection device based in Ultraviolet-C radiation. Initially, it
was designed for the periodic conditioning of culture rooms. It offers the capacity to be
remotely programmed using an Android mobile device and it has an infrared detection
security system that turns off the system when triggered. The system here described is
easily scalable to generate higher ultraviolet dosages adding more UV-C lamps. The exper-
imental tests showed the very high effectiveness of this device to eliminate high bacterial
inocula. The sanitizing method employed by this device affects a very wide range of
microorganisms and it has several advantages respect to chemical based-sanitizing meth-
ods. The total cost to make this open source device is below USD 180 and it is easily
customizable which is different respect to proprietary commercial devices actually avail-
able. This device represents an open source, secure, fast and automatized equipment for
room disinfecting. The device is configured in less than three minutes and it does not
require continuous monitoring.
Ó2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY
license (http://creativecommons.org/licenses/by/4.0/).
Specifications table
Hardware name Programmable and low-cost ultraviolet room disinfection device.
Subject area Biological Sciences (e.g. Microbiology and Biochemistry)
Educational Tools and Open Source Alternatives to Existing Infrastructure
Hardware type Biological sample handling and preparation
Other [culture room disinfection]
Open Source License Creative Commons Attribution-ShareAlike 4.0 International License.
Cost of Hardware USD 176.40
Source File Repository https://doi.org/10.17632/cjppyp5j3n.2
1. Hardware in context
Since the last years, mobiles systems based on UV-C radiation have been used for cleaning and disinfecting hospitals
[1–4]. The contribution of this equipment to the conditioning of hospital areas makes these systems useful for other kinds
of spaces that require periodical disinfecting. The spaces which require control of the presence of microorganisms need effec-
tive, fast and economical controls, and also, that can be used on a frequent basis. When the growth of microorganisms is not
https://doi.org/10.1016/j.ohx.2018.e00046
2468-0672/Ó2018 The Authors. Published by Elsevier Ltd.
This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
⇑
Corresponding author.
E-mail address: marcelb@fcien.edu.uy (M. Bentancor).
HardwareX 4 (2018) e00046
Contents lists available at ScienceDirect
HardwareX
journal homepage: www.elsevier.com/locate/ohx
under control, they can interfere with the experiments carried in such spaces. For example, our group has several plant cul-
ture rooms designated to provide optimal conditions for plant growth. However, these conditions tend to promote contam-
inations with unwanted microorganisms, such as bacteria and fungi, that once established, are very difficult to eradicate. To
avoid or minimize the use of chemical agents, potentially aggressive to the surfaces of culture rooms and to minimize the
impact on the environment that can result from these agents, our group has chosen to include in the work routine, a peri-
odical irradiation of the culture rooms with UV-C, in order to eliminate and prevent biological contaminants. This practice
has been effective and requires less personal than the manual cleaning and disinfection based on chemical agents. UV-C radi-
ation inactivates microorganisms causing DNA damage by producing cyclobutane pyrimidine dimers (CPDs), altering DNA
structure, and thus interfering with DNA replication [5,6]. According to the World Health Organization Global Solar UV Index,
the UV region covers the wavelength range from 100 to 400 nm and is divided into three bands: UV-A (315–400 nm) UV-B
(280–315 nm) and UV-C (100–280 nm). Depending on its wavelength, intensity, and method of application, there are differ-
ent applications of ultraviolet light, for example, tanning, phototherapy, curing of materials, studies of UV aging for acceler-
ated weathering of materials, technical inspections using the luminescence or fluorescence induced by UV light, and
disinfection [7]. UV-C light, which is absorbed by the atmosphere, represents the most lethal wavelength for a wide spec-
trum of microorganisms. The maximum germicidal power of the ultraviolet radiation is at wavelengths near 260 nm and
it drops dramatically below 230 or above 300 nm. The ultraviolet light was discovered in 1801 and since the discovery of
the germicidal effect of this radiation in 1878 [8] it prompted its application for the microbial control. As early as 1903,
the UV-C germicidal effect was the basis for Niels Finsen to achieve the Nobel Prize of Medicine [9] and until today new
forms are being invented to apply this radiation for microorganism control [10–12].
In addition to UV-C irradiation, other methods of disinfection for large areas include the use of gaseous agents (formalde-
hyde, ethylene oxide, etc.) which are hazardous and require an air flow pattern. Likewise, liquid agents, such as sodium
hypochlorite are also employed for disinfection purposes, but these must be carefully removed after being applied and
may damage exposed materials (for example, electronic devices). Other methods include the use of ionizing radiation, but
in addition to being hazardous, they require very specialized equipment [13]. Although since mid-20th century UV treat-
ments have been used for disinfection (reviewed in [14]), only in recent years this technology became more reliable as a con-
sequence of the incremented lifespan of UV lamps. the use of UV-C is a chemical free and low-cost procedure, which
represents a green alternative method for disinfection.
2. Hardware description
The use of commercial proprietary equipment for UV-C radiation of the environment entails a significant cost to acquire
the equipment and to repair it because it has a proprietary technology. Most of the available equipment use low-pressure
mercury lamps to produce UV-C radiation. These lamps can be acquired separately and used in the open source device
described here. We have constructed a UV-C radiator device that includes a microcontroller board, an Arduino UNO board
[15]. This microcontroller board is used to operate the system and permits the establishment of security measures which
are frequently restricted to the most expensive property models [16]. In addition, the equipment can be operated from a
wide range of Android mobile devices with suitable screens and processing capacity (tablet, cell phone, etc), taking advan-
tage of the ubiquity of these devices, and lowering the cost of its construction.
Some of the uses that can be given to this device are:
Culture room disinfection.
Material curing.
Lowering the microbial load in food supplies (example: vegetables).
3. Design files
Design file name File type Open source license Location of the file
Design file 1 APK file Creative Commons Attribution-
ShareAlike 4.0 International License.
https://doi.org/10.17632/cjppyp5j3n.2#file-
4930efee-0317-44e3-911a-e74893f72fe1
Design file 2 AIA file Creative Commons Attribution-
ShareAlike 4.0 International License.
https://doi.org/10.17632/cjppyp5j3n.2#file-
06204a99-1b4a-4e11-8b14-23dae8e21a18
Design file 3 MP4 file Creative Commons Attribution-
ShareAlike 4.0 International License.
https://doi.org/10.17632/cjppyp5j3n.2#file-
87fd7b4c-9787-445c-99e5-b86652e9940e
Design file 4 INO file Creative Commons Attribution-
ShareAlike 4.0 International License.
https://doi.org/10.17632/cjppyp5j3n.2#file-
8562c96e-035a-4e80-8b36-9559173fae64
Design file 1, is the APK file for the Android app which commands the device.
Design file 2, contains the source code for the app which commands the device.
Design file 3, contains a video showing the operation of the device.
Design file 4, contains the source code to program the Arduino UNO board of the device.
2M. Bentancor, S. Vidal /HardwareX 4 (2018) e00046
4. Bill of materials
The full bill of materials is shown in Table 1. The main components of the device and the fully assembled device are
shown in Fig. 1.
Table 1
Full bill of materials required to make the UV-C device.
Component Number Cost per
unit -USD
Total cost
-USD
Source of materials Material type
Arduino UNO board 1 8.49 8.49 https://www.amazon.com/gp/product/B01AR7YJ3O/ref=oh_
aui_search_detailpage?ie=UTF8&psc=1
Electronic
Bluetooth module HC06 1 6.99 6.99 https://www.amazon.com/WINGONEER-Bluetooth-
Serial-Adapter-Replace/dp/B06XHG73JG/ref=sr_1_1?s=
industrial&ie=UTF8&qid=1521137776&sr=1-1&
keywords=hc06+bluetooth+module
Electronic
PIR sensor 1 6.99 6.99 https://www.amazon.com/Aukru-Pyroelectricity-
Raspberry-Microcontrollers-Electronic/dp/B019SX734A/
ref=sr_1_1_sspa?s=industrial&ie=UTF8&qid=
1521137843&sr=1-1-spons&keywords=pir+sensor
+arduino&psc=1
Electronic
Relay module (5 V) 1 5.80 5.80 https://www.amazon.com/gp/product/B00VRUAHLE/
ref=oh_aui_search_detailpage?ie=UTF8&psc=1
Electronic
LEDs 3 0.40 1.20 https://www.amazon.com/Diffused-10mm-mixed-
color-pack/dp/B077MB2F1M/ref=sr_1_fkmr0_1?ie=
UTF8&qid=1521138062&sr=8-1-fkmr0&keywords=led
+mixed+bag+-+10mm
Electronic
Resistors (100
X
) 3 0.01 0.03 https://www.amazon.com/1280pcs-Values-Resistors-
Assortment-Assorted/dp/B00H703OKE/ref=sr_1_2?s=
hi&ie=UTF8&qid=1521138134&sr=1-2&keywords=
resistors
Electronic
Passive buzzer 1 0.50 0.50 https://www.amazon.com/Passive-Terminals-
Electronic-Continuous-Arduino/dp/B07D8MQ9ZW/ref=
sr_1_1_sspa?s=hi&ie=UTF8&qid=1535822862&sr=1-1-
spons&keywords=Passive+buzzer&psc=1
Electronic
Double Sided PCB Board
Prototype (8 cm 2 cm)
1 0.40 0.40 https://www.amazon.com/Breadboard-TOOGOO-
Experimental-Boards-Strip/dp/B00UFMB3TK/ref=sr_1_
1?s=hi&ie=UTF8&qid=1521138300&sr=1-1&keywords=
pcb+board+experimental
Electronic
UV-C lamp (Phillips TUV-T8
30 W) with holder
420 80 https://www.amazon.com/dp/B002DQV9WM/ref=psdc_
495232_t1_B013A13TGC
Electronic
Holder or light fixture for
the UV-C lamps
45 20 https://www.alibaba.com/product-detail/t8-2ft-batten-
t8-fluorescent-light_1894464907.html?s=p
Electronic
220 V/5V, 1A electric
adapter
1 7 7 Local hardware store Electronic
Plastic box
(15 cm 12 cm 7 cm)
1 5 5 Local hardware store Plastic
Wheels 4 2 8 Local hardware store Metal and plastic
Wooden column
(98 cm 10 cm)
1 5 5 Local hardware store Wood
Wooden base
(56 cm 46 cm 2 cm)
1 4 4 Local hardware store Wood
Wires 4m 1 4 Local hardware store Other
Connection strip 1 1 1 Local hardware store Metal and plastic
Female AC power plug 1 3 3 Local hardware store Metal and plastic
Male AC power plug 2 3 6 Local hardware store Metal and plastic
Metal ring (30 cm 20 cm) 1 3 3 Local hardware store Metal
Total cost: USD 176.40.
M. Bentancor, S. Vidal /HardwareX 4 (2018) e00046 3
5. Build instructions
The construction of the device involved three stages: structural building, electronic assembling, and programming of the
microcontroller and the mobile application. The scaffold structure was made by attaching to a central column four holders
for UV-C germicide lamps (Phillips, model TUV T8), connected in parallel. The central column was placed on a mobile base,
and on its upper end, a metallic ring was attached to allow easy driving of the device and to bring support for the control
unit. In this way, the ring is connected to the bottom mobile base through a solid wooden column, which is strong enough
to tolerate the necessary push to move the device. A schematic view of the assembled model is shown in Fig. 2. The four UV-C
Fig. 2. Schematic view of the UV-C room disinfecting device. a) Assembling guide. The central column (1) was fixed using four screws. (2). In the lower part
of this base, four rotating wheels were placed (3). Four holder lamps (4) were attached around the central column (1) using screws. The four lamps were
wired, guiding its wires through the control unit (6) which was installed inside the supporting metal ring (5) which was fixed on the upper part on the
central column. Different views of the device are shown: front view (b) side view (c) and perspective view (d).
Fig. 1. UV-C room disinfection device assembled, main components are indicated.
4M. Bentancor, S. Vidal /HardwareX 4 (2018) e00046
lamps were connected in parallel between them. The supply wire was connected to the control unit using a male plug. The
control unit was placed on the upper part of the device.
The control unit is based on an Arduino UNO board; this gives the order to the switch to turn on the UV-C lamps using an
electromechanical relay. An HCO6 Bluetooth module is used to communicate with the board using Bluetooth devices. Three
LEDs were installed to indicate it functional estate:
Connected to the electric supply (green LED)
Bluetooth connection established (blue LED)
UV-C lamps activated (red LED)
The red LED is combined with a passive buzzer to start a warning sequence just before the activation of the UV-C lamps. In
this way, the user is warned about the imminent switching on of the UV-C lamps. To emphasize this critical warning, a char-
acteristic sequence combining flashing of the red LED and sound from the buzzer was included in the code for the Arduino
board.
Because the UV-C radiation is harmful to humans, a PIR sensor was added as a security measure. In this way, the device is
automatically turned off when a user is near. When the PIR detects a moving warm body turns off the UV-C lamps. To reac-
tivate the lamps, the device requires the intervention of the user. This PIR sensor brings a conical coverage encompassing 110
degrees towards the front part. The device needs to be oriented toward the entry door of the room which is desired to irra-
diate. Eventually, it is possible to add more PIR sensors to increase the infrared coverage of the device.
The electrical powering of the device is through the electrical network (AC 220v) which provides energy for the UV-C
lamps and feeds the Arduino board and the rest of the electronic circuit through a USB adapter (5 V). The electrical diagram
of the connections is shown in Fig. 3. The source code for the Arduino board is provided in Appendix A. The relay controls one
of the conductors used to energize the UV-C lamps. External and internal views of the control unit are shown in Fig. 4.
Finally, a mobile application was developed to control the disinfecting unit. This app was designed using the MIT app
inventor 2 tool [17]. The interface of this application is used for connection to the device via Bluetooth, and for selecting
the irradiation time. The radiation time can be set using a drop menu or allowing the manual introduction of the time lapse.
The application shows the running timer during the irradiation period. Since switching on and off of the UV lamps depend on
the Android device commands, during these moments the Android device must remain connected to the UV-C device via
Bluetooth. In the main screen of the application is possible to consult reference values of UV-C dosages required to eliminate
the 99.9% of different inoculums according to publically available data [18,19]. A more extensive list of UV-C dosages is pos-
sible to obtain in the provided references. Characteristic sounds and alerts were added to the app to indicate switching on or
off the UV-C lamps.
Detailed build instructions. Tools list provided to each sub-heading
Fig. 3. Wiring diagram. Except for the UV-C lamps, all the components were assembled inside the plastic box of the control unit. R1, R2, and R3 are resistors
(100
X
). Relevant connections are labeled.
M. Bentancor, S. Vidal /HardwareX 4 (2018) e00046 5
5.1. Mobile base and main structure
Phillips screwdriver, plier drill
Four gyratory wheels were fixed using screws to a wooden table (56 cm 46 cm). At the center of the table, a wooden
column was attached using four screws. In an equidistant way, four lamp holders were attached around the central wooden
column employing screws. These holders were wired appropriately to connect in parallel the four lamps. The power supply
for the lamps was attached to the column and it was connected in one extreme to a female plug to facilitate subsequent con-
nection to the control unit. To the upper part of the column, a metal ring was attached using screws. The function of this s
ring is to support the control unit and to facilitate the transport of the UV-C device.
5.2. Control unit
Soldering iron, hot glue gun, plier, Phillips screwdriver, electric drill, and conic drill
The LEDs, resistors, and buzzer were mounted over the surface of the double-sided PCB board prototype according to the
wiring diagram depicted in Fig. 3. Circuits tracks were traced using the iron soldering. This PCB board was attached, using hot
glue, inside the plastic box of the unit control, and three holes were made in such a way that the three LEDs emerged outside
the control unit. A hole was made in the door of the plastic box, using the conic drill, to locate the sensor of the PIR module. In
one of the sides of the plastic box, the Bluetooth module was attached using hot glue, and the relay module was attached
using screws. The Arduino UNO board was attached inside the plastic box using Phillips screws. All connections were made
using cables according to the connection depicted in Fig. 3.
The supply cord was assembled installing a male plug in one extreme, for plugging into a regular electric wall socket. The
other extreme of the cord was introduced into the plastic box of the unit control through a hole made with the drill. This cord
was bifurcated using a connecting strip, from which the following connections were made: 1) the UV-C lamps were con-
nected directly to one of the poles, the other pole was connected directly to the lamps but through the relay module, using
the output labeled in the module ‘‘normally open”. 2) Using a second connecting strip, the 220 V/5V power adapter was con-
nected to the Arduino board through a USB cable. The rest of the electronic components of the control unit were energized by
the Arduino board according to the wiring diagram showed in Fig. 3. The assembled control unit is showed in Fig. 4. By open-
ing the control unit and disconnecting the USB from the 220 V/5V adapter it is possible to connect a computer to load the
script on the Arduino board. Before loading the script, it is necessary to disconnect the TXD and RXD terminals from the Blue-
tooth module. After loading the script, both terminals need to be reconnected, and the USB cable reconnected to the electric
adapter. After this, the unit control door is closed and the device is ready to work.
Fig. 4. Control unit of the UV-C room disinfection device. External view (left). Internal view (right). 1, a plug for connect to the UV-C lamps. 2, Power supply
cord. 3, LED to indicate the connection to the electric supply. 4, LED to indicate an established Bluetooth connection. 5, LED to indicate the lighting of the
lamps. 6, buzzer and PCB board for connections of the components. 7, relay module. 8, Arduino UNO board. 9, the output for the power supply cord for the
UV-C lamps. 10 and 12, electrical connections using connection strips. 11, power adapter (220 V/5V) to energize the Arduino board and associated modules.
13, PIR sensor.
6M. Bentancor, S. Vidal /HardwareX 4 (2018) e00046
6. Operation instructions
1) Install the app ‘‘UVC disinfection device” in your android mobile device. Previously, the Android device has to be
enabled to install apps from unknown sources. Plug the UVC disinfecting device to the electrical network. The green
LED will turn on
2) Execute the app previously installed on your mobile device.
3) Connect to the UVC disinfecting device by Bluetooth. Once the connection is established, the blue LED will turn on.
4) Select the radiation time, you can manually set the time or choose it from the drop menu.
5) Click on the ‘‘Activate” button. The app shows the estate of the UVC device as ‘‘Activated”. The red LED will turn on and
start blinking. This light will be accompanied by the sound of the buzzer emitting several short beeps. After the last
longer beep, the UVC lamps will turn on. The red LED will switch from blinking to continuous and will stay on as long
as the UVC lamps are functioning.
6) The app will switch off the device upon completion of the programmed time. The app will show the estate of the
device as ‘‘Inactivated” and the red light will turn off. Alternatively, the device may be switched off by clicking on
the ‘‘stop” button. The timer may be reset by clicking on the ‘‘reset” button.
7) The dosage reference table shows some reference values for UVC dosage required to disinfect up to 99.9% of different
kind of microorganisms.
8) Exit the app by clicking on the ‘‘Exit” button. The blue LED will turn off.
The main use of this sanitizer is to reduce or eliminate a wide range of microorganisms existing in a specific area. The
reference values for dosage are provided to allow the user estimation of the minimum exposure time that needs to be used.
These values are only indicative, and therefore, the optimal exposure time should be determined experimentally according
to the needs. The dosages values indicated in reference [13] can be used to estimate the required exposure time according to
the following simplified method:
The UV-C dosage received by surface unit (D, expressed in J/cm
2
) at a given distance (r) from the sanitizer, depends on the
power of the emitted UV-C light (P, equal to 48 W for our device) according to this equation:
D¼ðP:tÞ=ð2
p
:L:rÞ ð1Þ
where L is the length of the UV-C lamps (89 cm) and t is the exposure time expressed in seconds.
Based on this equation, the exposure time can be calculated as follows:
t¼ð2
p
:L:r:DÞ=Pð2Þ
Using this method, a tool to estimate the minimum exposure time to reach the desired dosage for a certain distance from
the device (Fig. 5b) was developed and is available in the initial screen of the app controlling the device.
Fig. 5. Capture screens of the developed app for the UVC disinfecting device. a) Splash screen b) Tool for estimate the exposure time. c) Main screen.
M. Bentancor, S. Vidal /HardwareX 4 (2018) e00046 7
7. Validation and characterization
The dimensions of the device are 50 45 130 cm (width depth height). The bottom base has four wheels to facil-
itate movement. Fig. 6 shows the UV-C device in operating mode. A video of the operating device is provided as supplemen-
tary material. Any part of the environment which is illuminated by the device directly receives UV-C radiation. It is
recommended to irradiate the room using the device in different successive positions. The use of this device does not replace
other methods for disinfection but contributes with an additional measure for the destruction of airborne organisms or inac-
tivation of microorganisms on surfaces.
In order to evaluate the effectiveness of the UV-C device, Petri dishes with a known inoculum of Escherichia coli strain K12
W3110 were irradiated. Under the tested conditions it was possible to almost eliminate all bacteria in the cultures. In a first
assay, a Petri dish with a non-selective medium, low salt Luria-Bertani (composition: 5 g/L sodium chloride, 5 g/L yeast
extract, 10 g/L tryptone, 15 g/L agar) were inoculated with 200 mL of liquid culture of E. coli (1,9 E
4
colony forming units/
mL). These plates were placed vertically and open, one meter away from the UV-C device. One half of the plate was covered
by aluminum foil. After one hour of exposure to the device, the plates were closed and incubated overnight at 37 °C. Fig. 7
Fig. 6. UV-C device working. A video showing the setting up of the device is included in the supplementary material.
Fig. 7. Petri dishes inoculated with 200 mL of a liquid culture of E. coli strain K12 W3110 (1,9 E
4
CFU/mL) were irradiated during one hour at one meter from
the UV-C device. The right half of the plates were kept covered with aluminum foil during this period, while the left half of plate was kept discovered.
Duplicates of the experiment are shown, after being incubated the irradiated plates at 37 °C overnight.
8M. Bentancor, S. Vidal /HardwareX 4 (2018) e00046
clearly only shows bacterial growth in the zone of the plate that was not exposed to the UV-C rays (covered by aluminum
foil), while no growth was observed in the exposed side of the plates. These results show that the UV-C device was able to do
fully eliminate bacterial growth in an inoculum of 10
4
bacteria when plates were irradiated for one hour from a distance of
one meter.
In another test, plates inoculated with E. coli K12 W3110 were placed open and vertically at one meter and two meters
from the UV-C device, and after one-hour irradiation, they were closed and incubated overnight at 37 °C together with a non-
irradiated Petri dishes inoculated likewise. Fig. 8 shows that the device was able to completely kill the bacteria in the irra-
diated plates also when the procedure was done at a distance of two meters
To evaluate the required exposure time to kill the bacteria, low salt Luria-Bertani Petri dishes inoculated with 10
4
E. coli
K12 W3110 were placed at one meter from the device and withdrawn at 15-minute intervals for one hour. This experiment
shows that a 15 min exposure is enough to eliminate the inoculum (Fig. 9).
7.1. Cost analysis
Actually, the proprietary market offers disinfecting units based in UV-C lamps that use mercury or xenon. The first ones
are the most common and less expensive, and this kind of lamp is used in the device here presented. The required materials
Fig. 8. Effect of exposure to the disinfectant device on plates inoculated with 200 mL of a liquid culture of E. coli K12 W3110 (1,2 E
3
CFU/mL) placed at 1 m
and 2 m from the device and exposed during one hour. Duplicates of the experiment are shown.
Fig. 9. Effect of different times of UV-C exposure over plates inoculated with 200 mLofE. coli K12 W3110 liquid culture (1,9 E
3
CFU/mL) placed at one meter
from the UV-C device. Triplicates of the experiment are showed.
M. Bentancor, S. Vidal /HardwareX 4 (2018) e00046 9
to make this open source device are easily available locally and its cost, below USD 180, turns this in a very competitive
device because it represents a more than 80% save compared with proprietary commercial devices with similar functions
(see Table 2). If xenon lamps based devices are considered, the saved amount is even higher. These savings are in the order
of other reported savings for other kinds of open source hardware [20].
In this cost analysis the labor cost for the assembly of the device is not considered, however, and in the same way that for
other open source hardware [20] after being developed the prototype unit, this device can be replicated by any person with
basic knowledge about electronics. So this device is not only easily accessible to many laboratories that require room UV-C
disinfection but also can be used for training purposes on the use of this kind of microcontroller or the assembly of open
source hardware.
7.2. Perspectives and discussion
The development of this low-cost open source hardware expands access to this kind of equipment to be used in health-
care facilities, culture rooms, or any other environments that need to be periodically disinfected. Furthermore, this device is
useful for training human resources in building this device thus enabling the easy repairment of the equipment. Moreover,
because the know-how for structure building and programming of the hardware is provided here, this gives the opportunity
to the users to improve this equipment or scale it up to build higher power models if it is necessary. A possible improvement
maybe adding a time use register of the lamps. According to the lamp manufacturer, these have a useful life of 9.000 h,
whereafter such time, a 10% lumen depreciation is observed. This could be done by registering the use time in the EPROM
memory of the Arduino board, then.
Furthermore, the UV-C device could be constructed having more than four UV-C lamps, in case that it is found necessary. The
presented design easily allows its modification to include multiple circuits to operate all or a subset of lamps simultaneously.
The UV-C lamps model (Phillips, TUV T8) was chosen because according to the maker it has a special glass which filters
out the 185 nm ozone-forming radiation [21]. However, a post-irradiation time period or aeration is suggested to avoid
exposure to ozone in the newly disinfected room.
Because the UV-C apparatus is controlled by an Android mobile device using a Bluetooth connection, it is possible to
extend to a greater operational range, using Wi-Fi to connect to the mobile device, which in turn, controls the UVC apparatus.
In our lab, the UV-C apparatus is controlled via Bluetooth using an Android Tablet. In addition, we use the app Teamviewer
[22] to remotely connect to the tablet via Wi-Fi, and through this, operate the UV-C room disinfection device.
In our case, the UV-C device is used to disinfect plant culture rooms, the device is located near the middle of the room,
where the distance to the walls is 1.5 m. The UV-C dosage delivered by this device has been effective to disinfect these rooms
and is in the range of the required intensity, the four UVC lamps have 48 W as total UV-C output power.
8. Conclusions
An open source UV-C room disinfection device was made with similar functions to proprietary commercial systems. The
presented model can be easily scaled up, modifying its structure (adding more UV-C lamps) and programming (editing the
open source code of the Arduino board and/or of the Android application), achieving savings for more than 80% respect to the
price of similar proprietary commercial equipment.
Declarations of interest
None.
Acknowledgments
The authors acknowledge to Mr. Luis Eduardo Casas the assembly of the structural support of the UV-C device. We
acknowledge Dr. Magela Laviña and her group for providing the bacterium E. coli K12 W3110 strain.
Table 2
Comparative prices of UV-C room sanitizers according to information provided by its sellers.
Model Manufacturer Source Price (USD)
TURBO-UV MRSA-UV http://www.mrsa-uv.com/products.html 1.000
GermAwayUV mobile CureUV https://www.cureuv.com/products/germawayuv-mobile-uvc-surface-
sterilizer
1.200
UV CARE room sterilizer UV CARE http://www.uvcare.net/room-sterilizer/ 1.850
HELIX 450XL MRSA-UV http://www.mrsa-uv.com/helix-450xl.html 5.000
MRS33-88 American Ultraviolet https://www.americanultraviolet.com/germicidal-healthcare-
solutions/mobile-room-UVC.html#mrs33
13.995
MRS45-12 American Ultraviolet https://www.americanultraviolet.com/germicidal-healthcare-
solutions/mobile-room-UVC.html#mrs45
19.995
10 M. Bentancor, S. Vidal /HardwareX 4 (2018) e00046
Appendix. -A code for Arduino board.
M. Bentancor, S. Vidal /HardwareX 4 (2018) e00046 11
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