International Journal of Research In Science & Engineering
Volume: 1 Issue: 4
e-ISSN: 2394-8299
p-ISSN: 2394-8280
A CLOSED LOOP INSTRUMENT SYSTEM FOR MONITORING AND
CONTROLLING OF HUMAN BLOOD SUGAR
Monica P Suresh1, Dr. A. Vimala Juliet 2, Dr. J. David Suresh3
Research Scholar, Department of EEE, St. Peter’s University, monicasrsh@yahoo.co.in
2
Professor & Head, Department of I & C, SRM University, vimlala2@yahoo.co.in
3
Veterinary Surgeon,Department of Surgery, Dave’s Pet Hospital davidsrsh@gmail.com
1
ABSTRACT
In this article a MEMS based instrumentation system for measuring blood glucose levels and controlling it by injecting
insulin non-invasively is presented. Traditional methods for measuring blood glucose involve collecting blood samples
by puncturing the ball of the person’s finger or fore arm which is a painful process. This article presents a system that
is non- invasive method of measuring blood glucose and injecting insulin which is done trans-dermally unlike
traditional methods, which involve injecting insulin which also is painful. Measurement of blood glucose is done using
electro-enzymatic sensors. If the level of glucose in blood is above the threshold level, then insulin is injected from a
micro pump, which is actuated electrically. The micro pump consists of a piezoelectric membrane which acts as the
actuator to pump insulin through micro-needles in to the body non- invasively. Micro-needles just puncture the dermis,
which does not cause much pain to the patient. The design proposed here is a combination of a glucose sensor, which
is placed at a distance away from the point of insulin injection, and a micro pump integrated with micro needles for
painless delivery of insulin to the patient. The controller gets its input from the sensor and depending on the level of
glucose sends a signal to the micro pump to initiate pumping of insulin, according to pre- set values. The controller
controls the frequency of glucose measurement as well as the level of insulin, if required, that is injected. This system
requires not much effort on the patient’s part, to monitor or control blood glucose level.
Keywords: Electro-enzymatic, micro-needles, piezo-electric actuator, trans-dermal.
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1. INTRODUCTION
Today there are lot of techniques available for measuring blood glucose levels and for injecting insulin. But
the techniques available require blood for testing for blood glucose. This makes the procedure painful. This paper
presents a compact MEMS based instrumentation system,that is non-invasive for both measuring and controlling of
blood glucose level by injecting insulin trans-dermally.
An electro-enzymatic sensor is used to sense the level of glucose. Electro-enzymatic glucose sensors are
designed using Gold (Au) electrodes on glass substrates to reduce the cost of production and simplify the fabrication
process. This output of this sensor actuates an insulin delivery system. Insulin is delivered trans-dermally through an
array of micro needles. The chip consists of an array of high aspect ratio (up to 50), high density (1 x 106 needles/cm2)
hollow micro needles to be inserted into the skin up to a depth of 100 microns with insulin reservoirs connected to the
needles. This system offers scope for mass production and therefore becomes an attractive method in combating
diabetes.
2. GLUCOSE SENSOR
The method presented here for measuring blood glucose level does not require actual blood. The level of
blood glucose in human sweat is proportional to the level in human blood. Therefore human sweat is used to measure
the level of blood glucose level. Electro-enzymatic sensor is used for glucose sensing. These are sensors that produce
IJRISE| www.ijrise.org|editor@ijrise.org
International Journal of Research In Science & Engineering
Volume: 1 Issue: 4
e-ISSN: 2394-8299
p-ISSN: 2394-8280
electrical signals proportional to the change in physiological parameters. In the presence of glucose oxidase enzyme,
glucose reacts with oxygen and water and produces Gluconic acid and hydrogen peroxide.
Glucose + O2 + H2O GOX
Gluconic acid + H2O2
Glucose in human sweat, when it comes in contact with the atmospheric air produces gluconic acid and
hydrogen per oxide. When a positive electric potential is applied, under the presence of a catalyst like platinum, gold
or silver, two hydrogen per oxide molecules are oxidized into oxygen water and four electrons as given in the equation
below.
2H2O2 Au/Pt O2 + 2 H2O + 4eThe current (electrons) produced in this reaction is proportional to the concentration of hydrogen per oxide,
which in turn is proportional to the glucose concentration. Using Gold or Silver in these electro chemical or electro
enzymatic sensors reduces the cost drastically, when compared to those sensors that use platinum. Gold electrodes are
easier to pattern using traditional micro fabrication techniques. The maximum value of current produced by these
electrodes for a glucose level of 600 mg/dl is 300nA.
The glucose sensor is placed on a piezo electric actuator which is activated by applying a suitable electric
potential. Glucose levels are regularly measured by applying an electric potential to the piezo electric actuator. The
Piezo electric actuator is as shown in Fig -1.
Fig-1: Glucose Sensor
On applying an electric potential across the piezo electric cantilever beam, the beam bends and the electrode
comes in contact with the sweat. This gives a measure of glucose level in the sweat which is proportional to the level
of glucose in the blood.
3. CONTROLLER CIRCUIT
A closed loop circuit for controlling the glucose sensing circuit and the insulin delivery system is as shown
in fig -2
Fig- 2: Controller Circuit
The controller at regular intervals of time, sends a signal to the sensing circuit, which initiates sensing of
glucose level. The maximum output of the glucose sensor is fed back to a signal conditioning circuit which converts
the proportional current to voltage. This voltage is now fed back to the controller, which is compared against a
reference voltage. If the compared voltage is higher than the reference voltage, the controller sends a signal to the
IJRISE| www.ijrise.org|editor@ijrise.org
International Journal of Research In Science & Engineering
Volume: 1 Issue: 4
e-ISSN: 2394-8299
p-ISSN: 2394-8280
insulin delivery system which initiates insulin delivery trans-dermally. A VLSI based controller is chosen, as their
power supply is very small compared to the ones required by common microcontrollers.
4. INSULIN DELIVERY SYSTEM
Insulin delivery system consists of a diaphragm based micro pump assembly with a set of micro needles as
shown in Fig -3. The micro pump can be operated by applying a voltage to the diaphragm. The diaphragm, which is
made of a piezo electric material like PZT can be deflected up and down. When a positive signal is applied to the
diaphragm it deflects upwards and when a negative signal is applied to the diaphragm it deflects downwards. When
the diaphragm moves upwards a suction pressure develops within the pump chamber and liquid gets sucked into the
chamber. When the diaphragm moves downwards the fluid in the chamber gets pumped out through the outlet, and
through the micro needles into the skin. Micro needles are designed for insertion into human skin for painless
transdermal drug delivery. Because the skin’s outer stratum corneum provides the primary permeability barrier, micro
needles need to only pierce past this 10 to 15μm thick layer to administer drugs that can diffuse through highly
permeable viable epidermis to capillaries found in the superficial dermis below.
Fig-3: Miro pump Assembly
3. CONCLUSION
The problem with diabetic care is having to check blood sugar levels constantly and to keep sugar levels
within the normal limits insulin has to be injected. Both of these prove to be painful as both monitoring and controlling
by injecting insulin involve pricking. This keeps lot patients from following up the treatment regularly. The patients
also have to be careful to do both of these at the right intervals of time. Most of the patient being medical novices, do
not bother to carefully follow the schedule prescribed (i.e. checking glucose level and injecting insulin). Now the
system suggested does not require the patient to do anything consciously as monitoring and controlling is automatic
and the whole exercise is painless. The cost of the device also can be reduced due to batch production. Using gold
instead of platinum in the glucose sensor brings down the cost. The cost can still be brought down by exploring
possibility of using silver in place of gold.
The above system can also be configured for use in animals like dogs and pigs, which also develop diabetes
related problems.
IJRISE| www.ijrise.org|editor@ijrise.org
International Journal of Research In Science & Engineering
Volume: 1 Issue: 4
e-ISSN: 2394-8299
p-ISSN: 2394-8280
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
Eun-Joo Park, Jacob Werner, Devina Jaiswal, Andrew G Webb and Nadine Barrie Smith, “Feasibility of a closed
loop controlled non- invasive ultrasonic glucose sensing and insulin delivery system” IEEE International
Ultrasonics Symposium Proceedings, 2009.
J Bin Ma Sheng Liu, Zhiy in Gan, Guojun Liu, Xinxia Cai, Honghai Zhang, Zhigang Yang, “A PZT Insulin
Pump Integrated with a Silicon Micro Needle Array for Transdermal Drug Delivery” Electronic Components and
Technology Conference, 2006.
Naoyuki Nakanishi, Hidetake Yamamoto, Kazuyoshi Suchiya,Yasutomo UETSUJI and Eiji NAKAMACHI,
“Development of Wearable Medical Device for Bio-MEMS”.
Baojian Xu, Defeng Zhu, Dongfeng Yin, Qinghui Jin, Shen Gao and Jianlong Zhao, “Pyramid –Shaped Tips
Based Polymer Microneedles for Transdermal Drug or Nanoparticle Delivery”, Proceedings of the 7th IEEE
International Conference on Nanotechnology, Aug 2 – 5, 2007.
Jasbir N Patel, Bonnie Gray, Bozena Kaminska and abyron Gates, “Electro- Enzymatic Sensor for Non-Invasive
Glucose Measurement”, IEEE, 2007.
Nitaigour Premchand Mahalik, “MEMS”, Fourth Edition, 2007, Tata McGraw-Hill Education Private Ltd.
Chang Liu, “Foundations of MEMS”, Pearson International Edition, 2006.
P. Rai Choudry“ MEMS and MOEMS Technology and Applications”, Prentice Hall of India, 2012.
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