Received: 30 June 2017
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Revised: 14 September 2017
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Accepted: 4 October 2017
DOI: 10.1111/jfpe.12640
ORIGINAL ARTICLE
Design and development of microcontroller based instrumentation for studying complex bioelectrical impedance of fruits using electrical impedance spectroscopy A. Chowdhury1 | S. Datta1 | Tushar K. Bera2
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D. Ghoshal1 | Badal Chakraborty3
1
Department of Electronics & Communication Engineering, N.I.T. Agartala, Tripura, India 2
Department of Medical Electronics, B.M.S, College of Engineering (B.M.S.C.E.), Bangalore, India
Abstract Electrical impedance spectroscopy (EIS) is an electrical impedance technique to characterize the fruits and vegetables in terms of their frequency dependent bioimpedance profile. Standalone, portable, and low-cost instrumentation is always preferred for conducting EIS procedures. This article reports the studies on the design and development of a Microcontroller based portable
3
Department of Post Harvest Engineering, B. C.K.V, West Bengal, India
impedance measurement system to conduct the EIS studies on the fruits during ripening and storage. The proposed laboratory based EIS system is developed with a Microcontroller ATmega16, a
Correspondence Badal Chakraborty, Department of Post Harvest Engineering, Faculty of Agricultural Engineering, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, West Bengal, India. Email:
[email protected] Funding information The Institution of Engineers (India)
Direct Digital Synthesizers based constant current source AD5930, a current to voltage converter, a low pass filter, and a DSO. To test and evaluate the developed system, the cucumber impedance is studied under the storage condition using EIS to characterize the cucumber freshness from the electrical impedance data. The real parts, imaginary parts of the cucumber impedance are calculated and the Nyquist diagrams are analyzed to study the equivalent circuit analysis. The developed system is compared with a standard impedance analyzer and it is observed that the results obtained from the developed system closely match with the data measured by the commercial impedance analyzer. The developed system is also found suitable for EIS studies of fruits, vegetables, and other biological tissues. The developed system is found low-cost, fast, and user friendly. PCB based version of the proposed system with display unit will be found as a portable, standalone, and EIS system suitable for outdoor measurement in agricultural-field applications.
Practical applications Microcontroller based low cost electrical impedance spectroscopy (EIS) has been developed and is studied for EIS based fruit ripening analysis. The system is compared with the standard commercial impedance analyzer and it is found suitable fruit ripening characterization, vegetable freshness detection, and health studies of other biological tissues. The microcontroller based EIS system is found portable, low cost, fast, and user friendly device which can be used in laboratory, cultivation fields, cold storages and shops and markets. The developed system allows nontechnical person to operated and collect the data from fruit and vegetable samples. The system acquired data significantly correlate the bioimpedance variation with the ripening states which can be potentially utilized to study the fruit ripening noninvasively at low cost. Hence the product-form of the developed devise could even be operated by field persons, farmers, and other common men to evaluate the fruit ripening and vegetable freshness.
1 | INTRODUCTION
1992; Orazem & Tribollet, 2008; Zhang, Bera, Woo, & Seo, 2014) is a noninvasive, fast, and low-cost technique of material characterization
Electrical impedance spectroscopy (EIS) (Almuhammadi, Bera, &
technique which can be efficient used to characterize the materials on
Lubineau, 2017; Barsoukov & Macdonald, 2005; Bera & Nagaraju,
the basis of its impedance. Due to its significant capability of electrical
2011a; Bera, Nagaraju, & Lubineau, 2016a; Bera et al., 2014; Macdonald,
impedance based material characterization, EIS has been applied in
J Food Process Eng. 2018;41:e12640. https://doi.org/10.1111/jfpe.12640
wileyonlinelibrary.com/journal/jfpe
C 2017 Wiley Periodicals, Inc. V
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CHOWDHURY
ET AL.
biomedical engineering (Bera, 2014; Bera & Nagaraju, 2011b; Bera,
Datasheet, 2017 Analog Devices) based constant current source
Nagaraju, & Lubineau, 2016b; Bera et al., 2013; Birgersson, Birgersson,
AD5930 (Analog Devices, Inc.) (Data Sheet, AD 5930, 2017 Analog
&
2007;
Devices), a gain stage, a current to voltage converter, a low pass filter,
€ thlingsho € fer, Ulbrich, Hahne, & Leonhardt, 2011; Ruiz, Zamora, & Ro
and a digital storage oscilloscope (DSO). The developed system has been
Felice, 2014; Sammer et al., 2014), material engineering (Grassini,
applied on the cucumber samples during its storage for several days and
Corbellini, Parvis, Angelini, & Zucchi, in press; Grossi, Lanzoni, Lazzarini,
the cucumber freshness is studied from the measurement of electrical
, 2012; Greuter & Blatter, 1990; YanLong, Bera, Lubineau, & & Ricco
impedance and phase angle. The real part (R), imaginary part (X), and
Yang 2017a; 2017b; He & Mansfeld, 2009; Morrison, Sinclair, & West,
Nyquist diagrams (R vs. X plot) (Bera & Nagaraju, 2013; Bera et al.,
2001; Pulido et al., 2017), chemical engineering (Adachi, Sakamoto, Jiu,
2016a, 2016b) are obtained using the amplitude and phase angle of the
Ogata, & Isoda, 2006; Echabaane, Rouis, Bonnamour, & Ouada, 2013;
electrical bioimpedance of cucumber. The performance of the developed
Kern, Sastrawan, Ferber, Stangl, & Luther, 2002; Longo, Nogueira, De
system is studied on the cucumber samples and the results are com-
Paoli, & Cachet, 2002; Lee, Hwang, Mashek, J. J., & Mason, 1995; Song,
pared with the data collected by a precision impedance analyzer. It is
Jung, Lee, & Dao, 1999; Wang, Moser, & Grätzel, 2005), civil engineering
observed that the results obtained by the developed device closely
(Christensen et al., 1994; Ribeiro et al., 2011), and other fields of applied
matched with the results obtained by the impedance analyzer. The
sciences and engineering (Almuhammadi et al., 2017; Bera et al., 2014).
developed system is capable to measure electrical impedance of fruit tis-
EIS is found as a widely used method suitable for investigating biological
sue samples between a frequency ranges from 50 Hz to 100 kHz with a
tissues non-invasively (Arpaia, Clemente, & Romanucci, 2008; Bera,
constant amplitude sinusoidal electrical excitation.
Ollmar,
2012;
Chakraborty
et
al.,
2015;
Keshtkar,
2014; Bera & Nagaraju, 2011b; Bera & Nagaraju, 2013; Bera et al.,
Like any other materials, electrical impedance of the biological tis-
2016a, 2016b; Birgersson et al., 2012; Clemente, Arpaia, & Manna,
sues changes with tissue electrical properties which are influenced by
2013; Clemente, Romano, Bifulco, & Cesarelli, 2014; Keshtkar, 2007;
the tissue composition as well as the frequency (f) of the applied elec-
€ thlingsho € fer et al., 2011; Ruiz et al., 2014; Sammer et al., 2014). Ro
trical excitation (Bera et al., 2016a, 2016b). Thus the fruit impedance
Impedance spectroscopy can also be used for food materials such as
changes with the fruit tissue anatomy and physiology (Chowdhury
meat (Bai et al., 2017; Oliver et al., 2001; Zhao et al., 2017), fish (Niu &
et al., 2017a; Chowdhury et al., 2017c). As the electrical properties of
Lee, 2000; Oliver et al., 2001), bread (Bhatt & Nagaraju, 2010;
the plant tissues changes with a change in the fruit anatomy and physi-
Daikuzono et al., 2017) and fruits and vegetables (Bera & Nagaraju,
ology, a number of studies (Bauchot, Harker, & Arnold, 2000; Bean,
2011c; Bera, Bera, Chowdhury, Ghoshal, & Chakraborty, 2017; Chowd-
Rasor, & Porter, 1960; Chowdhury, Bera, Ghoshal, & Chakraborty,
hury, Singh, Bera, Ghoshal, & Chakraborty, 2017b; Chowdhury, Bera,
2015; Harker & Dunlop, 1994; Harker & Forbes, 1997; Harker &
Ghoshal, & Chakraborty, 2017a; Chowdhury, Bera, Ghoshal, Chakra-
Maindonald, 1994; Hayden, Moyse, Calder, Crawford, & Fensom,
borty, & Naresh Kumar, 2017c; El Khaled et al., 2017; Rehman, Izneid,
1969; Liu, Fang, Zheng, Cosic, & Cao, 2007; Liu, 2006; Jackson &
Basem, Abdullah, & Arshad, 2011; Repo, Paine, & Taylor, 2002; Voz ary
Harker, 2000; Juansah, Budhiastra, Dahlan, & Seminnar, 2012a;
, 1998; Me szaros, 2007) in terms of their frequency dependent & D-ne
szaros, 1969; Retheep & Nikhil, 2013; Juansah et al., 2012b; Me
electrical impedance calculated from the boundary voltage-current data
Rehman et al., 2011; Jasmine Rose, Pamela, & Rajasekaran, 2013;
measured by an array of surface electrode and an electrical impedance
} , 2010; Zhang & Willison, Varlan & Sansen, 1996; Vozary & Benko
measuring instrumentation. EIS has been adopted by a several research
1991; Zheng, 2009) have been conducted on the electrical impedance
groups for investigation of fundamental electrical properties of fruits and
based analysis of fruits and vegetables to study, analyze, and character-
vegetables during ripening and storage. Though a number of commercial
ize the maturity, ripening states, and freshness. Even the different parts
instruments like impedance analyzer (Hoja & Lentka, 2008), LCR meter
of fruit tissues behave differently the bioimpedance at various frequen-
are available for impedance measurements and EIS studies, to conduct
cies under an alternating excitation, and hence the EIS procedure
the EIS procedure sometimes a standalone, portable instrumentation is
reveals information about the physiological changes occurring inside
always preferred for flexibility, portability, and ambulatory or outdoor
fruits and vegetables during ripening and storage by correlating the
measurement. Also, for agricultural applications and the applications for
fruit impedance with the change in physiology. Though the impedance
fruit freshness analysis in shops and market places a low cost and reliable
measurement could be made with any electronic instruments capable
instrument is required. Moreover, for real-time impedance measurement
of measuring the voltage current data along with the phase displace-
on the fruits and vegetables attached to the plants and trees a portable,
ment, the EIS data are collected by an electrical impedance measuring
light-weight, and user friendly instrument is and low-cost. In most of the
instrument called impedance analyzer or LCR meter. For bioimpedance
cases, the commercial instruments are not suitable to carry outside and
measurement also, instruments like LCR meter or Impedance analyzer
impedance measurement on fruits and vegetables attached before har-
are used along with some suitable surface electrodes arrays. Though
vesting are very difficult. In this direction, an impedance measuring
the commercial instruments are available with the capability of imped-
instrumentation (MIMI) is developed to study the EIS techniques and the
ance measurement and analysis, but for development of laboratory
developed system is applied on the fruits for analyzing the ripening and
based standalone impedance measurement instrumentation is found
freshness during their storage. The proposed MIMI system has been
advantageous for several reason such design flexibility, portability, cost
developed with a Microcontroller ATmega16 (Data Sheet, 2010,
effectiveness, and ease of interface and control. Sometimes the size
ATmega16 Microcontrollers), a Direct Digital Synthesizers (DDS
and weight of commercial devices are found disadvantage in some real
CHOWDHURY
FIGURE 1
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ET AL.
3 of 13
Fruit impedance measurement procedure: (a) four-electrode technique, (b) two-electrode technique
time application and some on-field experiments of the impedance mea-
To obtain the fruit impedance (Zf), the voltage current data are
surement. Moreover, for bioimpedance measurement of fruits and veg-
required to be collected either by applying a voltage signal to the fruit
etables in outdoor fields or outside the laboratory the commercial
sample or by injecting a constant amplitude current signal using surface
instruments are not suitable to use whereas the laboratory based
electrodes. When the voltage signal is applied on the fruit sample
instrumentation is very suitable to apply due to their extremely light
developed current signal is measured whereas if a current signal is
weight and portability. In this context, a microcontroller based simple,
injected as the applied signal, the developed boundary potential data
low cost, lightweight prototype instrumentation impedance measuring
are collected. Both the procedure could be conducted as either four
device has been designed and developed for bioimpedance measure-
electrode method (Figure 1a) or two electrode method (Figure 1b)
ment and tested and evaluated with the fruit samples. The previous
(Bera et al., 2016a, 2016b) and the impedance data are calculated by
works (Anand, Amit, Ruhi, & Pahuja, 2010; Sagar & Quazi, 2012; Hoja
dividing the voltage data by the current amplitude (Ohm’s Law). If, for a
& Lentka, 2009; Puchalski & Brusewitz, 1999; Radil, Pedro, & Cruz
fruit sample, a constant current (If) injection produces a surface poten-
Sera, 2005; Rose, Pamela, & Rajasekaran, 2013; Hakan et al., 2009;
tial (Vf), the fruit impedance (Zf) will be given by:
Amer Atta, 2014; Zhang, 2007) are generally found with AD5933 (Analog Devices, Inc.) (Data Sheet, AD 5933, Analog Devices) based imped-
Zf
