In this paper we describe a new data acquisition (DAQ) system for pharmacology experiments involving isolated muscle contraction. The system is composed of hardware acquisition unit and computer software for analysis of signals representing muscle contractions. As compared to mechanoelectrical DAQ systems of other constructions, the advantages of the new system include a high sensitivity (in the order of 1 µN), a wide range of forces recorded (1 µN to 100 mN), linearity throughout the whole range, easy assembly, low costs, long-term calibration stability, good dynamic characteristics and full control graphical interface. The device can be readily adjusted to actual experimental conditions and a variety of muscle preparations. Experimental validation of our DAQ inside the Clinical Pharmacology Department at Mansoura University Faculty of Medicine showed that it can record contractions of isolated muscle preparations with good precision and accuracy. Accordingly, the DAQ system design presented herein with its dedicated software is largely suitable for isolated muscle experiments in both teaching and research in biomedical fields

Dahab, Gamal M.

Fouda, Abdel-Motaal

Qutb, Mohamed H.

Corepaedia Publishing Services by Avicenna (E-Journals)

© 2018, The Authors Adv Med Med Res, 2018;1(1):19-24
ISSN 2535-2210
INTRODUCTION
Experiments utilizing isolated muscles including skeletal, 
smooth, and cardiac muscles are central component of re-
search involving screening of new drugs, as well as demon-
stration of drug effects on tissues in the practical classes of 
undergraduate pharmacology curriculum in medical, phar-
maceutical, and science colleges worldwide [1]. In these ex-
periments, the isolated muscle preparation is usually fixed 
at one end within the organ bath, and the other end is at-
tached to data acquisition system (DAQ) consisting of a iso-
metric/isotonic transducer that converts mechanical force/
displacement value into analogous electrical signal which 
then passes to a processing unit at which the signal is am-
plified, noise-reduced, and digitized before being displayed 
on screen by specialized computer software or recorded on 
a graph paper for remote analysis. Different models of DAQ 
systems for isolated tissue preparations are available in dif-
ferent technology forms. The PC-based DAQ provide a more 
powerful and flexible solution in both experimental research 
and teaching purposes than traditional graph paper systems 
[2]. 
A wide variety of simulation software and android ap-
plications have recently introduced in the cyberspace to fill 
the gap in experimental class teaching, however, concerns 
have arisen against the use of these simulation software in 
the teaching of laboratory classes as they do not enhance 
ABSTRACT
In this paper we describe a new data acquisition (DAQ) system for pharmacology 
experiments involving isolated muscle contraction. The system is composed 
of hardware acquisition unit and computer software for analysis of signals 
representing muscle contractions. As compared to mechanoelectrical DAQ 
systems of other constructions, the advantages of the new system include a 
high sensitivity (in the order of 1 µN), a wide range of forces recorded (1 µN to 
100 mN), linearity throughout the whole range, easy assembly, low costs, long-
term calibration stability, good dynamic characteristics and full control graphical 
interface. The device can be readily adjusted to actual experimental conditions 
and a variety of muscle preparations. Experimental validation of our DAQ inside 
the Clinical Pharmacology Department at Mansoura University Faculty of Medicine 
showed that it can record contractions of isolated muscle preparations with good 
precision and accuracy. Accordingly, the DAQ system design presented herein 
with its dedicated software is largely suitable for isolated muscle experiments in 
both teaching and research in biomedical fields.
Key words: data acquisition system; isolated muscles; experimental pharmacology 
DAQ; load cell sensor.
Cite as: Fouda AM, Qutb MH, Dahab GM. Design and validation of new data 
acquisition system for isolated muscle experiments: Application to pharmacology 
teaching and research.  Adv Med Med Res. 2018;1(1):19-24.
Design and Validation of New Data Acquisition System 
for Isolated Muscle Experiments: Application to 
Pharmacology Teaching and Research
Original Article
Abdel-Motaal Fouda1, Mohamed H. Qutb2, Gamal M. Dahab3
1Associate Professor of Clinical 
Pharmacology, Mansoura University 
Faculty of Medicine, Mansoura 35516, 
Egypt. 
2Freelance electronics engineer, 
Mansoura 35111, Egypt.
3Professor of Clinical Pharmacology, 
Mansoura University Faculty of 
Medicine, Mansoura 35516, Egypt.
Corresponding author
Abdel-Motaal Fouda
Email: foudaamm@mans.edu.eg
Tel: 0020501113974766
History
Date submitted: Jan 18, 2018
Accepted: Jan 30, 2018
Published online: Feb 7, 2018
Available online at
www.manspub.com
Copyright
© The Authors. This is an open access 
article distributed under the terms of 
the Creative Commons Attribution 4.0 
International License.
www.manspub.com
Adv Med Med Res, 2018; 1(1):19-24
ISSN 2535-2210
Open Access
Fouda et al. 2018Design and validation of DAQ system for biomedical experiments
© 2018, The Authors Adv Med Med Res, 2018;1(1):19-24
ISSN 2535-2210
20
the physical skills of students nor implicit understanding 
for working experiments in the laboratory [3]. Additional-
ly, these simulation software could not be used for research 
purpose as they lack interaction with living tissue and dis-
play only programmed results stored in the application files 
for just demonstration.
Unfortunately, the medical instruments are much ex-
pensive, and one PC-based DAQ system for isolated muscle 
experiments may cost thousands of dollars. This may add 
another challenge to teaching practical pharmacology to un-
dergraduate students as it would be difficult to obtain mul-
tiple units to match the increased number of students even 
in small group teaching. Recognizing this fact, a survey of 
medical graduates revealed that while a majority considered 
pharmacology as the most important basic science, they also 
recognized the pharmacology laboratories as the most bor-
ing and least useful practical laboratories [4]. Therefore, the 
need for efficient, flexible, and economic solutions that help 
in teaching practical laboratory classes to undergraduate 
students, as well as in medical research, is strongly required.
In this article we describe and validate a new versatile 
and low-cost, digital DAQ system for isolated muscle experi-
ments that does not utilize piezoelectric transducers or com-
plex expensive technology. This new DAQ system consists of 
acquisition unit and dedicated software. The low cost, effi-
ciency, and flexibility of the design presented herein enables 
it to be used widely in all experiments involving different 
types of isolated muscles preparations. Finally, we used sim-
ple technical terms and avoided complexities of mathemat-
ical equations of the acquisition unit components’ working 
principles aiming at encouraging students and teachers to 
build this simple DAQ system and use it in their practical 
classes or home experiments.
MATERIALS AND METHODS
Device construction
The circuit represented in Fig 1 utilizes double bending 
beam load cell sensor which measure tension force of mus-
cular tissue. The load cell sensor is a changeable component 
to adapt to ranges of muscle force from 0 to 750 g. The sensor 
is connected to special amplifier and noise filter circuit. The 
output goes to programmed microcontroller to send the data 
to dedicated computer software. The load cell, connected to 
the muscular tissue under test, converts tension forces into 
microcurrent which will be then amplified and filtered to 
eliminate potential noise before entering to a microcontrol-
ler. The microcontroller sends digitized data via universal 
serial bus (USB) to computer software with graphical inter-
face mounted on Dell Inspiron n5010 laptop with Intel core 
i3 processor, 4.0 GB RAM and built-in HD graphics on Win-
dows 7, 64-bit OS (Microsoft Corp, USA). We used Arduino 
configuration as communication device between computer 
and hardware using analog input to feed software with signal 
information (Fig 3).
Calibration and verification
The system was calibrated and verified by performing three 
verification tests: 
Repeatability test: was done to make sure that there is 
no deviation of the repeatability due to some interactions of 
the environment with the sensor. The same weight (1, 5, 10, 
20, 50, 100, 200 g) was added and removed several times and 
the changes in the scale rated capacity were recorded [5].
Creep test: was done to detect any tension that will re-
lax due to the application of the weight. The test was per-
formed by adding a weight on the scale and waiting for 5 
min. During the waiting time the changes in the scale rated 
capacity were recorded [6].
Linearity test: weights are added step by step on the scale, 
then removed. Readings are compared to calibrated value of 
the weight to detect any deviation of linearity or hysteresis 
that could be the indicator of an incorrect calibration [5].
Isolated smooth muscle experiments
The new DAQ system was subjected to a number of valida-
tion experiments inside the Clinical Pharmacology Depart-
ment at Mansoura University Faculty of Medicine, to ensure 
sensitivity and reliability in live tissue experiments. These 
experiments included isolated rabbit intestine, guinea pig il-
eum, and rat uterus. Experiments on isolated rabbit intestine 
were conducted according to the protocol of Jespersen et al. 
[7]. Experiments on isolated rat uterus were conducted ac-
cording to the protocol of Darios et al. [8]. All animal works 
were conducted in accordance with Mansoura University 
Institutional Research Board and the Guide to the Care and 
Use of Laboratory Animals (8th edition, 2011, The National 
Academic Press, Washington, DC, USA).
Fouda et al. 2018 Design and validation of DAQ system for biomedical experiments
© 2018, The Authors Adv Med Med Res, 2018;1(1):19-24
ISSN 2535-2210
21
Fig 2. Graphical interface of operating 
software. The horizontal scale measures time 
in customizable units while the vertical axis 
measures muscle force in Newton. The right 
dashboard contains controls for variable 
analyzable data such as heart rate, recording 
speed, force units, wave amplitude and area 
under the curve (AUC).
Fig 1. Components of the electronic circuit. The 100 g load sensor in this circuit is connected to the inputs of differential amplifier which detects 
minimal voltage difference thereby amplifies the minimum load pressure on the sensor. The three operational amplifiers are connected in 
instrumentation amplifier (INA) configuration so the output of differential amplifier is forwarded to another operational amplifier to amplify the 
signal (2 parallel opamps are used for more stability).  The last stage is the filter circuit formed by R5+C3 which filter internal and external noise and 
provide smooth signal. D1+R6+Q1+R12 feed external light-emitting diode (LED) which provides visual feedback of sensor pressure. R10 is used 
for sensor balancing.
Fouda et al. 2018Design and validation of DAQ system for biomedical experiments
© 2018, The Authors Adv Med Med Res, 2018;1(1):19-24
ISSN 2535-2210
22
RESULTS
Calibration and verification
The new DAQ system was subjected to three basic tests to 
ensure precision and accuracy. The device showed high sen-
sitivity in recording tension forces in the order of 1 µN and 
a wide range of forces recorded (1 µN to 100 mN). Friction 
test showed no deviation of the repeatability with application 
and removal of the same weight (1, 5, 10, 20, 50, 100, 200 g) 
several times. Rresults of the creep testing showed that 60 
min creep for the load cell sensor is equivalent to about 0.03 
% to 0.05 % of the applied load. Linearity test was done to de-
tect any deviation of linearity or hysteresis that could be the 
indicator of an incorrect calibration. Experimental testing of 
linearity showed that the device is capable of recording mus-
cle forces between 1µN and 100 mN with good linearity over 
the entire range (Fig 4). The reported discrimination ability 
was about 1 mV which corresponded to a force of 1 µN.
Isolated smooth muscle experiments
Pharmacological experiments with isolated smooth 
muscles preparations revealed very good sensitivity and 
discrimination ability. The primary signal was precise and 
free of noise. The graphical interface of the software has 
functions to analyze the waves. Figures 5, and 6, show traces 
of recorded experiments.
DISCUSSION
Isolated organ bath experiments provide evidence for char-
Fig 4. Experimental testing of linearity showed that the device is 
capable of recording traction weight with good linearity over the whole 
range.
Fig 3. We used Arduino 
configuration as communication 
device between computer and 
hardware using analog input 
to feed software with signal 
information
Fouda et al. 2018 Design and validation of DAQ system for biomedical experiments
© 2018, The Authors Adv Med Med Res, 2018;1(1):19-24
ISSN 2535-2210
23
acterization of drug effect in biological tissues which can be 
directly translated to human studies [9]. Both teaching and 
research within the discipline of pharmacology common-
ly utilize experiments that require excised isolated organs 
or tissues to allow for the study of drugs and their interac-
tions within these tissues [1]. Unfortunately, implementa-
tion of the practical component in pharmacology teaching 
to undergraduate students is a tedious task as it is difficult 
to obtain multiple units to match the increased number of 
students even in small group teaching and there is need to 
ensure cost efficiencies. 
The DAQ system described herein is widely applicable 
for various biological experiments involving isolated muscle 
contraction and may successfully replace devices used so far. 
The method is highly sensitive and easy to build up. It uses 
commercial small load cell sensor that can convert muscle 
tension into analogue signal. The acquired signal then passes 
to an electronic circuit to amplify, digitize, and reduce noise 
of the analogue signal. The resulted digital signal can be dis-
played and analyzed with computer software with graphi-
cal interface and wide range of functions. As compared to 
mechanoelectrical DAQ systems of other constructions, 
the advantages of our system include a high sensitivity (in 
the order of 1 µN), a wide range of forces recorded (1 µN to 
100 mN), linearity throughout the whole range, easy assem-
bly, low costs, long-term calibration stability, good dynam-
Fig 5. Representative recordings of isolated rabbit intestine showing the effect of different concentrations of acetylcholine (above) and adrenaline 
(below). Both traces show good discrimination of contraction waves. Both time and amplitude are measured on the X and Y axes respectively.
Fig 6. Representative recording of isolated rat uterine strip preparation 
showing the spontaneous contractions and the effect of both oxytocin 
and adrenaline. The recording shows good response rate of the sensor 
with no creep.
Fouda et al. 2018Design and validation of DAQ system for biomedical experiments
© 2018, The Authors Adv Med Med Res, 2018;1(1):19-24
ISSN 2535-2210
24
ic characteristics and full control graphical interface. The 
device can be readily adjusted to actual experimental con-
ditions and a variety of muscle preparations. The range of 
muscle contractions to be measured and/or dynamic proper-
ties of the recording unit can be customized by the selection 
of the appropriate load cell sensor.
Accuracy of DAQ systems concerned with recording 
forces such as muscle contractions depends on many factors 
including precision, repeatability, linearity and hysteresis. 
The concept of precision refers to the degree of reproducibil-
ity (or repeatability) of a measurement. In other words, if ex-
actly the same value (e.g. muscle contraction) was measured 
a number of times, an ideal sensor would measure exactly 
the same value every time. Likewise, load cell creep is the 
difference between initial response when force applied and 
the response at a later time [10]; accordingly, ideal sensor 
has minimal creep response. We performed both the friction 
and creeping test to ensure good precision and repeatability 
of our system. The readings of the two tests showed that the 
acquisition load cell sensor has very good precision and sta-
bility. Our results of creep testing showed that 60 min creep 
for the load cell sensor is equivalent to about 0.03 % to 0.05 
% of the applied load
Linearity is another characteristic of a measurement sys-
tem in which output is linearly proportional to the input. So, 
linearity is graphically represented as a straight line (a rela-
tion between input and output). In measuring muscle cell 
contractions the actual range of contractions will be 1µN – 
10mN. This range corresponds to deformations of ±1 x 10–3 
with a transmission linearity better than 0.8 % [11]. Experi-
mental validation of our data acquiring sensor showed that it 
can record muscle forces above this range with good lineari-
ty over the entire range. Accordingly, the load cell transducer 
design presented herein and its electronic circuit is largely 
suitable for dynamic measurements.
Ideal DAQ systems have good discrimination ability 
known as the ability to eliminate noise without negative ef-
fect on the measured signal. In our design, the noise could 
be efficiently reduced by filtering the high frequency noise 
using a low frequency filter at the output of the amplifier 
circuit, or by limiting the frequency characteristics of ampli-
fiers using suitable capacitors in feedback connection. The 
reported discrimination ability was about 1 mV which cor-
responded to a force of 1 µN.
In conclusion, we described in the article the technical 
and applied aspects of new and cost-effective DAQ system 
suitable for teaching and biomedical research concerned 
with isolated muscle contractions. The system is sensitive, 
precise, has good discrimination, repeatability and linear-
ity. The ease of construction and cost-effective value elect 
it to replace old kymographs utilizing smoky paper and the 
recent expensive units, and enable its manufacture on large 
scale to meet the expanding number of undergraduate stu-
dents in biomedical fields.
Conflict of interest 
The authors declare that they have no conflict of interest. 
Funding
This research received no specific grant from any funding 
agency in the public, commercial, or not-for-profit sectors.
REFERENCES
1. Kitchen I. Textbook of in vitro practical pharmacology. 
Blackwell Scientific Publications, Oxford, United Kingdom. 
1984.
2. Salini, Tranquilli and Prakash. “Design of Instrumentation 
for Recording the Electromyogram.” MQP Project EXC-0302. 
2003.
3. Hughes IE. Do computer simulations of laboratory practicals 
meet learning needs?. Trends in Pharmacological Sciences. 
2001; 22(2), pp71-74.
4. Naeem SS, Rizvi W, KumarA.  Revisiting undergraduate 
practical pharmacology. J Pharmacol Pharmacother. 2012; 
3(1): 76-9.
5. http://www.aicpl.com/brochures/loadapp.pdf
6. Mohamed MI, Hasan EH, Aggag G. Study of creep behavior of 
load cells. Measurement. 2009; 42:7, 1006-1010.
7. Jespersen B, Tykocki NR, Watts SW, Cobbett PJ. Measurement 
of Smooth Muscle Function in the Isolated Tissue Bath-
applications to Pharmacology Research. Journal of Visualized 
Experiments : JoVE, 2015;(95): 52324. Advance online 
publication. http://doi.org/10.3791/52324
8. Darios ES, Seitz B, Watts SW. Smooth muscle pharmacology 
in the isolated virgin and pregnant rat uterus and cervix. J 
Pharmacol Exp Ther. 2012, 341 (3) 587-596. 
9. Downey JM, Cohen MV. Why do we still not have 
cardioprotective drugs? Circulation J. 2009; 73(7): 1171-1177.
10. http://www.ni.com/white-paper/14860/en/
11. Load cell testing gets straight to the point”. Maritime Journal. 
Mercator Media. 20 December 2010.


Design and Validation of New Data Acquisition System for Isolated Muscle Experiments: Application to Pharmacology Teaching and Research: Submitted: Jan 18, 2018	Accepted: Jan 30, 2018	Published online: Feb 7, 2018

https://corepaedia.pub/index.php/ammr/article/download/493/458

Design and Validation of New Data Acquisition System for Isolated Muscle Experiments: Application to Pharmacology Teaching and Research: Submitted: Jan 18, 2018 Accepted: Jan 30, 2018 Published online: Feb 7, 2018

Abstract

Similar works

Full text

Available Versions

Corepaedia Publishing Services by Avicenna (E-Journals)