2. Research & Literature Review¶
Some Literature Review¶
The Human Bioelectricity¶
One of the most interesting secrets of human body, is bioelectricity. Human body is 70% water which is polarized solution and other elements in our bodies, like sodium, potassium, calcium, and magnesium, have a specific electrical charge. All of body cells use these charged elements or ions to generate electricity and to to conduct electrical currents simply by controlling the movement of the ions through the cell membrane. Electricity is required for the nervous system to send signals throughout the body and to the brain, to move, think and feel. Usually, brain electrical signals control the movement of muscules througout the body. However, there is another type of cells that generate elecricity by themselves these special cells are avaliable in the heart and referred to as "Sinoatrial Nodes (SA Nodes)".
The figure shows the anatomy of the heart. For more details regarding the heart and its electrical system, refer to the link.
The figure above shows the generic connection between the brain and body muscles.
Generally, in biomedical engineering the electrical signals from human body are reffered to as "Biopotentials".
Electrocardiography and its significance¶
Electrocardiogram or ECG is an electrical signal processing technique used as a diagnostic test to record and display the rhythm and the electrical activity of the heart. From observing different cardiac rhythm patterns, physicians can study the heart's electrical activity and can diagnose cardiac disorders. The electrical activity of the heart is being translated into line tracings on paper where the spikes and dips represent different waves generated from the pulsation of different types of cardiac tissues. The pattern of the ECG is periodically organized as P Wave followed by QRS Complex ending with T Wave. The P wave is a record of the electrical activity through the upper chambers or atria; QRS Complex is a combination of three different waves that represent the record of the movement of electrical impulses through the lower chambers or ventricles, and the T Wave shows the ventricular diastole or the electrical resting state of the ventricles. This pattern repeats regularly every 0.83s in healthy cardiac rhythm. The following gif shows the healthy cardiac rhythm.
The ECG is also used to measure the heart rate by finding the R-R interval as follow:
- Surface Electrodes
Generally, acquiring and extracting biopotential signals from the human body is quite challenging, due to the weakness of the body's signals, their high tendency to attenuation and sensitivity to be superimposed with noise. Consequently, the readout circuit designs should be very sensitive with accurate data acquisition system to detect signals. This system of biopotential electrodes should be precise enough to reject interfaces, noise and to provide effective filtering and amplification of the extracted biopotential signals extracted. Moreover, the biopotential electrodes system should be made electrically safe by designing circuits which operate at low current to ensure that they are not harmful. The first stage in a biopotential sensing system is surface electrodes. Surface electrodes measure the potential available from the surface of the skin. There are many different types of surface electrodes, but the most common ones are adhesive skin electrodes. Big adhesive surface electrodes are used for ECG signal acquisition. The following figure shows the different parts composing a surface electrode.
Another common method used for heart rate monitoring is through infra-red (IR) transmission and reception to detect the heart pulses (refer to the link).
This technique is commonly used in wearables such as Apple Watch, Fitbit, etc.
Textile electrodes are innovative advanced sustainable and longlasting solution compared to skin electrodes. Textile electrodes are made of conductive textile materials which are usually called "Smart Textiles" which have the capability to convert energy from physical form to electric energy. I came across a very interesting article by Wearic illustrating more about smart textiles. Below, I am listing some interesting research papers related to textile electrodes and how they are used in biometering; particularly, in electrocardiography.
- Textile Sensor System for Electrocardiogram Monitoring
- Direct patterning of organic conductors on knitted textiles for long-term electrocardiography
- Textile-Structured Electrodes for Electrocardiogram
- Washable and Reliable Textile Electrodes Embedded into Underwear Fabric for Electrocardiography (ECG) Monitoring
Gel Electrodes vs. Textile Electrodes¶
In order to understand how to such a proposed smart garment can be designed and used, I have done some market research to see what are the existing technologies. I came across a large number of companies designing smart clothing; however, the following brands represent ideas relevant to my proposed idea.
Most of the market products are using either textile electrode sensors or printed electrodes. For my application, I would like to explore more about the use of textile electrode sensors for biometering.
Users Engaged in the Design Process¶
In language, the term "Users" does not always mean the final target audience. According to dictionary, the most appropriate synonym of the final target users of a product is "End Users".
I came across an interesting article highlighting the significant role of end users to assist the producer users or designers to design something that can particularly solve their problems.
Image retrieved from the article.
I was also given the advice by Cecilia Raspanti to refer to their interesting publication in WAAG Community Users as Designers: A hands-on approach to Creative Research where they are showing real cases and how the user experience was useful in design.
At this point, I wanted to have another look at my empathy map and I need to validate it with real people by conducting interviews or surveys.
Another Look at the Empathy Map¶
I found a very interesting map in this research paper titled Designing smart garments for rehabilitation showing features and factors affecting the wearability of smart garment.
After that I looked again at my empathy map that I drafted during week 11. I changed the target users to a broader scale of people mainly to spread the awareness of personal health monitoring. The device can be used by makers, researchers, educators, etc as it is a research project for now and later will be developed into an open source and modular smart garment as a product. After resaching that the product can be adapted to different users for different purposes as open source and modularity features will give this room of freedom.
Going back to the wearability requirements and factors map, I have developed something similar with a particular focus from my empathy map.
What is the Added Value? Why this "Smart Garment" is needed?¶
Again having this research project with a design that is open source and modular is the added value. No Black Boxes!!
I have developed a survey with few questions and I have shared it with different makers, engineers and designers at the age range of 23-35 years from different FabLabs and maker spaces mainly in the Arab world. Questions and answers are shown below.
The last question was a short answer question stating; "How you envision the future for smart clothing?". Answers for this question were very interesting an many people were explining how they might be the appearance, size and level of comfort of the smart garments. Additionally, many people were expressing how the use of smart garments can replace the general appoinment to physicians and can even assist doctors to do their job with a clear history of vital signs.
From the results of the survey, I was very glad to see many of the user empathy map elements validated in the answers :] However, I was surprized to know that the majority of people are not aware of smart clothing concept and only 50% of the group are using smart wearable. On the other hand, most of the people have expressed that they would prefer to have the smart wearable place at the wrist or within the clothes. It was very exciting for me to see that most of the people prefer the modular design more than the regular design for a smart garment. Also majority of people are concerned about the practicality of wearing such a garment (i.e. washability, ease of use, etc), the sustainability of the fabrication and disposal, the cost and the battery life. Seeing all of that was completely alligned with the user empathy map that I have developed. Moreover, more than 40% prefer the garment to be made of cotton mixed with polyester and over 35% prefer to have it made of pure cotton. These two fibers can provide comfort and help regulating the body temperature which can be very practical for daily use.