Lab-on-Phone: A Participatory Sensing System

Jorge Mario Garzon Rey, Juan Manuel Soto Valencia, Antonio Garcıa Rozo, Fredy Segura-QuijanoDepartamento de Ingenierıa Electrica y Electronica

Centro de Microelectronica (CMUA) - Universidad de los Andes

Bogota D.C., Colombia

Email:{jm.garzon131,jm.soto569,angarcia,fsegura}@uniandes.edu.co

Abstract—This paper presents a novel approach defined aslaboratory on phone “Lab-on-Phone” which include the mainfeatures of “Human Centric Sensing”,“Participatory Sensing” and“Ubiquitous Computing” paradigms in a multiuser and multipur-pose acquisition, processing, storage and analysis chain infras-tructure. Lab-On-Phone includes a generic sensing module whichshares data with a Smartphone via Near Field Communication(NFC). The sensor measurements are processed and displayedby an Android application running in the same Smartphone,a web server stores the measured information sent by multipleSmartphones, considering privacy and security. Lab-on-Phonealso uses a set of web applications which allow accessing datafrom many different places and in any platform with Internetaccess.

Keywords—Human centric sensing,Participatory Sensing, Ubi-quitous Sensing

I. INTRODUCTION

ONE of the main motivations for developing new tech-

nologies is to increase humanity’s quality of life.

The Microelectronics Center at Universidad de Los Andes

(CMUA) has broad experience in developing micro and nano

sensors, and wireless sensor networks based on management

information systems including data bases and web servers [1]–

[7],. Sensors allow us to measure environmental variables and

keep a historical record via sensor network infrastructure [8].

In fact, this is the first step in understanding the environment

condition and therefore improving life quality.

Nowadays, it is not enough to measure the environment

around us. There is a new tendency known as Human Centric

Sensing which focuses on measuring the internal variables

of human body [9], which means people are paying more

attention and using more resources to know the status and

behavior of their own body. For example, people suffering

from respiratory diseases can be interested in the air quality

around them in order to avoid unwanted conditions. Diabetic

patients for example use devices to monitor their blood glucose

level in order to control critical levels and to help their

doctors improving treatments. Another common example are

heart rate monitors used by athletes. These devices are a

key for measuring performance and evaluate athlete’s health.

These examples have a common infrastructure, which is a

measurement device with possible storage system.

The Participatory Sensing System is a new paradigm of

sensor networks in which common people carry small devices

with sensors and a communication platform [10], [11]. All the

information is collected and stored in a central data base. The

main feature of this type of systems is the possibility to have

wide coverage and high precision when increasing the number

of devices. It will also give a real global measurement of

the environment state and might help to evaluate government

Policies about climate change or epidemic control.

The increasing use of laptops, tablets and phones with high

performance microprocessors and an integrated set of sensors,

generates the possibility of sensing and computing data at any

location [12]. This third paradigm is called Ubiquitous Sensing

and Computing. It implies the possibility of having a dis-

tributed network of computing taking advantage of commonly

used devices. In the same way, current sensing capabilities

can be extended by using complementary devices designed

for specific applications.

This paper presents a novel approach defined as laboratory

on phone “Lab-on-Phone” which includes the main features

of “Human Centric Sensing”, “Participatory Sensing” and

“Ubiquitous Computing” paradigms in a multiuser and mul-

tipurpose acquisition, processing, storage and analysis chain

infrastructure. Lab-On-Phone includes a generic sensing mod-

ule which shares data with a Smartphone via Near Field

Communication (NFC) [13]. The sensor measurements are

processed and displayed by an android application running

in the same Smartphone, a web server stores the measured in-

formation send by multiple Smartphones, considering privacy

and security. Lab-on-Phone also uses a set of web applications

which allow accessing data from many different places and in

any platform with Internet access.

In the next section, there is a description of the system

architecture and functionality. In Section III, early results are

presented for a validation based on commercial boards. Finally,

Section IV summarizes the presented approach and future

works.

II. LAB-ON-PHONE SYSTEM ARCHITECTURE

The Lab-on-Phone platform includes a complete chain of

acquisition, processing, transmision and storage. In Figure 1

a representation of the whole working system is shown. A

big network of multiple types of sensors that can be accesed

by state entities or common people may possibly help to give

reliable and updated data. In many fields the lack of reliable or

updated information regarding a particular problem is one of

the main reasons for not solving the issue. In order to achieve

978-1-4799-2507-0/14$31.00 c©2014 IEEE

this goal the system must have as many people subscribed as

possible, be easily adapting to the many variables people are

interested to monitor and should have an accessible and user

friendly interface.

Fig. 1. Participatory Sensing System.

Based on the previous study, the system we present is

designed to be used by anyone and for many kinds of ap-

plications. The first layer of the system is based on a Measure

Card, which is a small acquisition device with the size of

a credit card, with a capacitor sensor. The Measure Card

is enabled to sent measurements to a Smartphone via NFC

protocol. An Android application installed on the Smartphone

processes the sensor measurements and gives an on-site result

to the user. If the device has a data plan or Wi-Fi access, the

measurements are sent to a web server through this medium.

The web server stores the measurements information from

multiple Smartphones controlling privacy. Lab-on-Phone also

has a web application, which allows accessing data from

everywhere and from any platform with Internet access.

A. Measure Card: acquisition system and sensor

The Measure Card is a small board with a low-power

microcontroller, a Dual Interface Electrically Erasable Pro-

gramable Read-Only Memory (EEPROM - M24LR16E) and

an Interdigitated Capacitor Sensor (ICS) connected to the

microcontroller.

The ICS varies its capacitance according to the substance,

a fluid mainly, between the capacitance’s fingers. This type

of sensor is used in many applications as for example in

pressure measurement, in methanol detection or in food status

identification. Currently, in the Center of Microelectronics of

Universidad de los Andes research is being done to identify

adulterated liquor based on this tecnique. The ICS capacitance

is calculated measuring it’s discharge time with a micro-

controller circuit. In order to achieve this, the comparator

and timer modules of the microcontroller are used. Once

a capacitance value has been calculated the microcontroller

stores it in the Dual-EEPROM via I2C protocol.

The M24LR16E Dual-EEPROM is an 2 kbytes EEPROM

chip that can be accesed via ISO 15693 RFID protocol or

via I2C protocol. The ISO 15693 protocol is NFC compatible

so an NFC enabled phone can read or write data wirelessly

from or to the memory respectively. The minimum data

rate is 6.62 kbits/s and the maximum is 52.97 kBits/s. The

Measure Card has two additional features: the first is that it

can also measure temperature via the embedded temperature

sensor of the microcontroller and the second is that an ADC

channel is enabled for connecting any type of sensor giving

a voltage value. In Figure 2 a diagram of the Measurement

Card Arquitecture is shown.

Fig. 2. Measurement Card Arquitecture.

The harvesting strategy is possible by the wireless power

transmitted from the carrier signal of the NFC technology.

The proposed Measure Card is a low cost board with an own

Interdigitated Capacitor and it could be fed by the Smartphone,

avoiding the necessity of a battery thereby increasing the porta-

bility of the whole sensing system. The chip has an Energy

Harvesting option so the unused energy in the connection and

in the command transmission in RF mode can be used to

feed another electronic component like a Light-Emitting Diode

(LED) or an IC.

B. NFC protocol

The NFC Forum is the world association that established

all the set of specifications related with NFC Technology.

NFC devices can operate with RFID technologies like ISO/IEC

14443 (Type A and B) used by Mifare Type A (NXP smartcard

technology), Calypso (European Cards) or EMV (Europay,

Mastercard or Visa cards) cards; JIS6319-4 used by Felica

Cards (Sony Smartcard System); ISO15693 used by RFID

cards with a range up to 1.5 meters, obviously this will be

reduced if the card is read with NFC technology; or ISODEP

14443-4 which is a transmission protocol used in proximity

cards used for identification.

The dual interface Memory M24LR16E-A uses ISO15693

standard [14] which allows communication with more than

one tag at the same time, but it is not going to be a common

stage of our application. It also defines the structure of the

requests and responses that must be made for communication

between the memory and an NFC device.

C. Android application

Data tag acquisition is included with any device with

Android OS and NFC technology. The Android OS provides

an API to NFC to be accessed from the applications [15].

When an NFC tag comes close to the RF radio of the NFC

hardware, the operating system automatically parses it and

notifies applications designed to manage NFC tags related to it.

The API is specifically designed for operations with NFC tags;

however, it also has basic support for other RFID protocols

including ISO 15693. Due to the simplicity of the ISO 15693

a library was developed in order to have a tool that can be

used in any Android application.

It is important to note that the tag is a passive compo-

nent so that all the transactions and changes in its memory

must be initiated by the NFC enabled device, in this case,

the Smartphone with Android OS. The application has been

designed in a way that when an ISO 15693 tag has been

discovered it automatically tries to connect to the device and

if it is registered, then the connection is made, otherwise,

a registration procedure must be made by the user before

fully establishing the connection. As soon as the connection

is made, the application begins to iteratively retrieve values

from the memory space where the sensor measurements are

stored by the microcontroller.

A basic communication protocol was developed to synchro-

nize the memory access made by the microcontroller and

the Smartphone. The information retrieved from the Dual-

EEPROM is displayed in a graph and sent via Wi-fi or

a mobile network (GPRS,3G,4G,etc) to a database server.

Additional information such as the position retrieved from the

GPS or the network, the tag identification, and the Smartphone

identification is appended to the message sent to the server. If

the Smartphone has a data plan, the measurements can be sent

to the server from anywhere with a mobile network access and

can be tracked from any computer with internet almost in real-

time. If the application does not have an available connection

to the internet; then the applications waits until it is available

to send it to the server. Additionally, all the measurements are

stored on the Smartphone internal or external memory.

D. Data base and Web server

All the measurements sent from the Smartphone are directly

stored in a Data Base Server. User information is appended to

each measurement so that it can be easily filtered when needed.

As the idea is that measurements taken from the sensors can

be tracked from practically anywhere and in an easy way a

web application was developed. The web application display

the information stored in the database and also shows all the

registered users able to send measurements to the database. In

the following figure the web server application interface can

be observed.

III. RESULTS

Figure 5 shows the implemented acquisition system using

an ANT1-M24LR16E antenna STMicroelectronics reference

board, including a MSP430G2553 on a LaunchPab board

Fig. 3. User Interface of Lab-on-Phone Android application. In the maininterface the user can visualize the last 30 seconds of measurements in thegraph. In the secondary interface the user can configure the location provider,the server connection, the location and visualize the registered devices.

Fig. 4. Web application interface. The measurements sent by the phone withinformation of the place, time, date and device identification are shown in atable. There is also a table showing the registered devices that are allowed tosend data to the server.

from Texas Instruments. The Interdigitated Capacitor Sensors

was designed and manufactured on the Printed Circuits Board

laboratory at Universidad de los Andes.

The Android Application was developed for Android 4.0.3

Version (Ice Cream Sandwich) and tested in a Sony Xperia

Sola with the same version of OS, NFC technology, GPS, Wi-

Fi, GSM, HSDPA, EDGE, GPRS, Dual-core 1 GHz Cortex-A9

and 512MB of RAM.

For the web server and the database, a LAMP Server was

installed in an Ubuntu Server 12.04.1. The apache version of

the web server is 2.2.22. The MySql version is 5.5.29. The web

Fig. 5. Implemented acquisition system. From left to right we show thesensor (Interdigitated capacitance) immersed in a solution, a microcontrollerand a dual interface EEPROM which is below the phone.

application was programmed to update its information every

30 seconds; so that users can monitor their measurements

almost instantly.

To validate the implementation we measure the discharge

time with the interdigitated capacitor for ethanol(99%),

methanol (99%) and a traditional Colombian Liqueur (Ethanol

27%) which give 64 ms, 69 ms and 72 ms respectively.

Fig. 6. Capacitance Measurements. The capacitance has a unique peak in adifferent frequency for each one of the solutions.

IV. CONCLUSION AND FUTURE WORKS

This paper presented a novel approach defined as “Lab-

on-Phone”, aiming to be a standard system for the recent

paradigm of Participatory Sensing. The sensing part of the

platform mainly uses an interdigitated sensor now used in

many commercial applications. Because there are other many

applications in which interdigitated sensors doesn’t fit, sensing

systems give the posibility of connecting a sensor that gives

its converted magnitud in voltage. These two features cover

a wide range of applications, an imperative factor in the

implementation of a truly, multivariable participatory sensing

system.

The entire measurement chain has been tested in all its

phases, including the sensor measurement, data adquision with

NFC communication, the mobile application, data transmis-

sion to the cloud and the server application.

The present work does not focus on the development of

sensors, but in the development of a novel platform taking

advantage of the Smartphone benefits showing the potential

a system like this would help to change and improve life of

every human being.

As future work, we propose the implementation of a web

application operating as a social network like Facebook, in

which people can share any parameter obtained by everyone.

We also recommend studing more comercial sensors or sensing

techniques that can be added to the measurement card which

could help to extend the platform applications. Finally we note

that the system currently works for measurements in which

adquisition and processing speed is very low, but for very

fast constant repeated measurements, improvements need to

be made.

ACKNOWLEDGMENT

The authors would like to acknowledge the CleanRoom

Laboratory and Printed Circuits Board Manufacturer Labora-

tory staff at Universidad de los Andes for their support.

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