A Novel Instrumentation System for Monitoring of Foot Ulcer

 

J. Samson Isaac, P. Kingston Stanley, P. Vijay Daniel, D. Pamela

Assistant Professor, Karunya Institute of Technology, Sciences, Coimbatore

 

ABSTRACT:

Measuring foot temperature is considered as an important for physiological studies as well as clinical investigations. It also helps in diagnosing and preventing many diseases like foot ulcer, diabetic neuropathy, etc. Foot ulcers are very common in diabetic population. In recent years, numerous observations have been reported and various methods of measurement have been employed. But all the existing systems were bulky and not more accurate. A system is proposed to measure the foot temperature very accurately to overcome the existing demerits. The proposed system introduces a novel temperature sensor, STS21 with 0.01°C accuracy for human foot temperature measurement. In addition, the temperature measuring system is made compact using Atmega328p microcontroller. The developed system is made to fit in to the shoe and the foot temperature is obtained from the subjects and displayed through PC. Foot temperature readings are taken from various subjects are analyzed to study the efficiency of measurement system.

 

 

 

1.    INTRODUCTION:

Diabetic foot ulcer (DFU) is the most common complication of diabetes mellitus that usually fail to heal, and leading to lower limb amputation. Patients have a reduced ability to feel pain which means that minor injuries may remain undiscovered for a long period. People with diabetes are also at risk of developing a diabetic foot ulcer [1]. Diabetic foot ulcers are a devastating component of diabetes progression and are caused by loss of glycemic control, peripheral neuropathy, peripheral vascular disease, and immune suppression. An estimated 15% of patients with diabetes are expected to develop diabetic foot ulcers. To date, DFU is considered as a major source of morbidity and a leading cause of hospitalization in patients with diabetes [2]. The most common pathway to develop foot problems in patients with diabetes is peripheral sensori-motor and autonomic neuropathy that leads to high foot pressure, foot deformities, and gait instability, which increases the risks of developing ulcers [3][4][5].

 

Numerous investigations have shown that elevated plantar pressures and temperature are associated with foot ulceration. Patients with DFU should be educated about risk factors and the importance of foot care, including the need for self-inspection, monitoring foot temperature, appropriate daily foot hygiene, use of proper footwear, and blood sugar control [6]. The validity of temperature sensor output was assessed by placing the instrumented shoe inside an incubator, controlled at 5 different temperatures ranging from 24° to 47°C to mimic conditions typical of an indoor environment and conditions that might be expected inside a shoe being worn [7, 8]. For example, moisture is believed to compromise skin integrity and contribute to pressure ulcer formation in elderly and bedridden individuals [9]. Additionally, some researchers have suggested that a localized increase in skin temperature may indicate inflammation and may help to identify tissue damage resulting from repetitive stress [10]. Various evaluation techniques are used in practice such as prick test, heat test, vibration test in podiatry. The Sudomotor Function Test (SFT) was developed as a clinical tool to demonstrate the risk of developing diabetic foot ulcers (DFU) in earlier stage detection [11]. Diabetic neuropathy exhibit a higher foot temperature that exhibits risk for foot ulceration. Ambient temperature and foot ulceration additionally influence foot temperature in such patients. Miniature temperature data loggers were used for the monitoring of foot skin and ambient temperature [12]. Autonomic evaluations under clinical study and nerve conduction reported the linear relationship of plantar skin temperature to diabetic neuropathy. Such incidence were found present in both feet of 25 control subjects and 29 (out of 69) diabetic patients (SSR+ group). This study indicated that the thermoregulatory sweating abnormality signified early sympathetic damage in diabetic feet [13]. Ulcer formation and proliferation in diabetic patients is an inability to sense the precursors of wound development in the extremities were monitored using a system design, and testing protocol on the soles of the shoe. Pressure and temperature sensors placed at the targeted high risk areas of an insole are used in conjunction with a data acquisition system to read the necessary data from the soles of patients' foot [14] were helpful in early diagnosis and prevention of amputation. In early detection stages recent technologies were evolved based on mobile thermal imaging system that can be used as an indicator for possible developing ulcers. The system was implemented [15] under MATLAB Mobile platform and thermal images were analyzed and interpreted was useful method to identify possible ulcers in diabetic patients was implemented in simulated conditions. Analyzing various literature the foot temperature could be a vital parameter for the subjects for early identification of foot ulcer. Further the proposed work we have designed a method to acquire temperature from the foot and also developed the hardware. This would help the podiatrist ease of use and diagnosis of ulcer.

 

2.    SYSTEM METHODOLOGY:

The measurement of foot temperature variations by placing sensor at insole and monitoring the temperature would be an effective method.

 

 

Figure 1 Block Diagram for Measuring Foot Temperature

The proposed system consists of sensing unit, control unit, display unit and finally the power supply unit were shown in Figure 1. The sensing unit consists of STS21 temperature sensor was low power device from Sensirion Manufacturer, Switzerland. Temperature sensors are placed on insole near heel region. The sensor can also be placed on any region of foot that is sensitive to temperature. The temperature sensor, STS21 has resolution of 0.01degree Celsius. Hence it is appropriate for measuring accurate change in the temperature. I2C protocol was used to acquire the data from the sensor. For more sensors are needed then bus repeater can be added and can be connected to Microcontroller. Only one I2C bus can be connected to all sensors from the master. The controller unit consists of Microcontroller. The microcontroller used was Atmega328P. From the master the temperature is displayed through PC through USB. The power supply unit was designed with 9V battery, 3.3 V regulator and 5V regulator. The setup was powered with different voltages such as: The sensor 3.3V, the controller 5V. The supply voltage is provided through portable dry cell 9V battery source. The system designed with highly accurate, low power and compact. Hence it can be useful in low cost and long life healthcare devices.

 

3.    RESULTS AND DISCUSSIONS:

A foot temperature measuring system was built finally with high accuracy. The temperature was acquired from the STS21 sensor by interfacing with microcontroller and output was displayed through PC in hyper terminal. The following Figure 2 shows the foot temperature measuring setup consists of (i) Microcontroller, (ii) USB interface, (iii) PC and (iv) Shoe Insole with sensor

 

	STS21 Sensor In Shoe insole

 

Figure 2 Experimental Setup of the Proposed System

 

The setup was kept inside the shoe and the subject was made to walk. The readings were taken for ten subjects and tabulated as shown in Table 1. The setup used to calibrate the temperature usingLM35 sensor. The LM35 sensor was placed on insole and connected to Arduino Uno. The ouput was displayed through Serial Monitor in Arduino Software are shown in Figure 3.

 

Figure 3 Foot Temperature Display in Hyper Terminal

 

Table 1 Temperature from Human Foot

S. No	SUBJECT	TEMPERATURE (°C)
1	Subject 1	34.72
2	Subject 2	35.23
3	Subject 3	34.40
4	Subject 4	33.11
5	Subject 5	35.74
6	Subject 6	34.90
7	Subject 7	33.21
8	Subject 8	34.30
9	Subject 9	32.45
10	Subject 10	35.78

 

 

Figure 4 Comparison between LM35 and STS21 sensor

 

The temperature acquired from STS21 sensor was compared with temperature acquired using LM35 sensor for calibration. The Figure 4 shows the comparison results. The chart clearly shows that STS21 sensor is more accurate than LM35 sensor. LM35 sensor is 0.5°C accurate whereas STS21 is 0.01°C. The proposed system gives the reliable temperature readings compare to the LM35 which could be preferred for clinical diagnosis in healthcare.

 

4. CONCLUSION:

In this work novel temperature sensor for measuring foot temperature was developed. The proposed system implemented with STS21 sensor gives the accuracy of 0.01°C for human foot temperature measurement. The temperature measuring system is made compact using Atmega328p chip as controller and placed insole of the shoe. The developed system is helpful in diagnosing, screening of foot ulcer there by preventing many diseases like ulcer, diabetic neuropathy and displayed through PC for further analysis.

 

5. REFERENCE:

1.      Aumiller, Wade D, Dollahite, Harry Anderson ,Pathogenesis and management of diabetic foot ulcers, Journal of the American Academy of PAs: May 2015 - Volume 28 - Issue 5 - p 28–34.

2.      Aalaa M, Malazy OT, Sanjari M, Peimani M, Mohajeri-Tehrani M, “Nurses’ role in diabetic foot prevention and care; A review”, Journal of Diabetes Metabolic Disorder. 2012;11:24.

3.      Formosa C, Gatt A, Chockalingam N., “Diabetic foot complications in Malta: prevalence of risk factors”, Foot (Edinb) 2012;22:294–297.

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5.      Sawacha Z, Gabriella G, Cristoferi G, Guiotto A, Avogaro A, Cobelli C. Diabetic gait and posture abnormalities: a biomechanical investigation through three dimensional gait analysis. Clinical Biomech (Bristol, Avon) 2009;24:722–728.

6.      American Diabetes Association. Standards of medical care in diabetes--2006. Diabetes Care. 2006;29 Suppl 1:S4–42

7.      Katrina S. Maluf, MSPT, Robert E. Morley Jr, DSc, Edward J. Richter, BS, Joseph W. Klaesner, PhD, Michael J. Mueller, PhD, PT, Monitoring in-shoe plantar pressures, temperature, and humidity: Reliability and validity of measures from a portable device, Arch Phys Med Rehabil Vol 82, August 2001

8.      Brand, PW., “Diabetes mellitus : theory and practice. in: The diabetic foot”,3rd ed, Medical Examination Publishing, New Hyde Park (NY); 1983: 829–849.

9.      Braden, B and Bergstrom, N. A conceptual schema for the study of the etiology of pressure sores. RehabilNurs. 1987; 12: 8–12

10.   Armstrong, DG, Liswood, PJ, and Todd, WF. “Contralateral limb during total contact casting. A dynamic pressure and thermometric analysis”, J Am Podiatr Med Assoc. 1995; 85: 733–737.

11.   Irene Sanz-CorbalánJosé LuisLázaro-MartínezEstherGarcía-MoralesRaúl Molines-BarrosoFrancisco Álvaro-AfonsoYolanda García-Álvarez“Advantages of early diagnosis of diabetic neuropathy in the prevention of diabetic foot ulcers”, Diabetes Research and Clinical Practice, Available online 27 December 2017. https://doi.org/10.1016/j.diabres.2017.12.018

12.   Piotr Foltyński, Beata Mrozikiewicz-Rakowska, Piotr Ładyżyński, Jan M. Wójcicki, Waldemar Karnafel, “The influence of ambient temperature on foottemperature in patients with diabetic foot ulceration, Biocybernetics and Biomedical Engineering, Volume 34, Issue 3, 2014, Pages 178-183.

13.   Pi-Chang Sun, Hong-Da Lin, Shyh-Hua Eric Jao, Yan-Chiou Ku, Rai-Chi Chan, Cheng-Kung Cheng, “Relationship of skin temperature to sympathetic dysfunction in diabetic at-risk feet”, Diabetes Research and Clinical Practice, Vol. 73, Issue 1, p41–46. February 17, 2006.

14.   T. Bernard,C. D'Elia,R. Kabadi, N. Wong, “An early detection system for foot ulceration in diabetic patients”,  IEEE 35th Annual Northeast Bioengineering Conference, April 2009. DOI: 10.1109/NEBC.2009.4967797.

15.   Luay Fraiwan, Mohanad AlKhodari, Jolu Ninan, Basil Mustafa, Adel Saleh, and Mohammed Ghazal, “Diabetic foot ulcer mobile detection system using smart phone thermal camera: A feasibility study”, Biomed Eng Online. 2017; doi: 10.1186/S12938-017-0408-X.

 

 

 

 

 

Received on 27.09.2018           Modified on 19.11.2018

Accepted on 11.12.2018         © RJPT All right reserved