In-Foot Monitor for Diabetic Foot - Paper Example

Complications arising from a diabetic foot are a major challenge for the healthcare system, patients and those who care for them. According to studies, about a quarter of people suffering from diabetes will in the course of their lifetime develop a foot ulcer. Many of these individuals will eventually be forced to have the foot amputated due to infection resulting from untreated ulcers. Given the technology available today, it is possible to design an in-shoe monitoring system for continuously monitoring at-risk ulcer areas based on certain known indicators. This essay identifies parameters that can be measured in a shoe environment to shed light on foot health. It will then present the design of an in-shoe monitor for the identified parameters.

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Any efforts at managing a diabetic foot should be directed towards prevention of foot complications such as infection, ulceration and amputation. Such preventive management is akin to preventing diabetes itself; something that involves early intervention with respect to how diabetes 2 progresses naturally. An ideal foot ulcer prevention program should consist of regular examination, non-invasive neurologic and vascular testing, and the right diabetic footwear. Implementing this program can minimize the chances of foot ulceration and risk of amputation by a significant percentage.

Diabetic Foot Ulcer Sensors Currently Available in Market

In recent years, there has been a substantial drop in the number of incidences involving diabetic foot amputations. However, there are still tens of thousands of individuals that are forced to undergo amputations each year as a result of diabetic foot ulcer. There are new technologies out there that, if applied well, could reduce this number significantly in the future as scientists search for more effective ways of detecting ulcers in the early stages and doing away with the need for amputation, or preventing serious injuries. For instance, there is a diabetic foot ulcer sensor launched by the Canadian health company known as Surrosense RX, which is designed in a way that it alerts someone of a looming foot ulcer prior to it breaking the skin. This device is made up of eight force sensors implanted in a shoes insole that records raw data, conducts an analysis. The sensor then changes it into a risk profile that is transmitted to a screen located on a wristband. A patient can perform active monitoring of damage to an ulcerous foot at all times. Surrosense RX uses a coin cell battery for operation that can last over six months, while the data can be sent to mobile device such as tablets and cell phones.

A frequently occurring side effect of diabetes is Peripheral neuropathy. It makes a patient lose feel of his or her feet, something that makes it quite hard to figure out when damage to a foot is taking place. There is a device known as SurroGait RX that has been designed to counter this side effect. It is a pressure-sensing insole capable of delivering a sensation to the back in order to highlight incorrect walking techniques that are likely to result in an ulcer. Better balance and gait significantly minimizes the chances of falling or the formation of a foot injury. Hence, by applying the phenomenon of neuroplasticity, a patient can get the ability to re-wire his or her brain in a way that it construes any back feelings as corrections for the feet.

There are numerous diabetic foot applications available in the market. One of the best is an Android/iPhone app developed by a company called Orpyx that can work hand-in-hand with the SurroGait and SurroSense gadgets. Tillges Technologies, a firm in Minnesota, has come with a wireless sensor known as PressureGuardian capable of detecting diabetic foot ulcers. However, this sensor is not practical for day-to-day use by patients. Rather, it is best utilized by professionals such as orthopedists or podiatrists. Podimetrics based in Boston designed a sensor implanted into a bath mat. The sensor assesses flow of blood in the feet for about 30 seconds and then sends alerts to a patient and his or her doctors.

Design of New Diabetic Foot Ulcer Sensor

When carrying out a design of pressure-sensing insole, the crucial parameters to put into consideration include the number of sensors, their size as well as locations. Foot pressure of an individual is affected by weight, foot deformities, gait patterns, and the walking speed. A high amount of pressure can cause the formation of ulcers. This necessitates the design of a system for acquiring foot pressure data that will monitor how pressure is distributed below the feet when someone is walking. It will also help figure out if an abnormal distribution of foot pressure occurs. A device for monitoring pressure will gather any information in a foot for both normal and abnormal positions while walking. A physician can use this device to diagnose the foot pressure distribution of a patient and then assess the best form of treatment. While the metrics mentioned above have been shown to be indicators of ulceration, none of them can be considered as reliable predictors. Presented below is a composite sensing device that can measure several metrics at once and offer an effective means of predicting any tissue failure. This device raises the number of metrics previously used while also boosting them.

The device undergoing design utilizes measuring metrics that can be of great use when it comes to predicting or determining ulceration. These metrics include humidity, temperature, acceleration, the applied force, galvanic skin response and the rotation rate. The instrumentation and sensors are fitted on each foot, while the data is transmitted to a Raspberry Pi that plays the role of a user interface and data reception controller- with this transmission being done via Bluetooth. Wireless technology is used; something that makes it possible for the system to be used in various environments such as a hospital, home, or gymnasium without the cumbersome inconvenience associated with wired sensors. Application of this device is not just restricted to monitoring diabetic feet. It also has the potential of monitoring other health conditions and athletic performance while also comparing its performance with other sensing devices in the market.

For the design, bioimpedance that is capacitively coupled can be added as a way of attaining inflammation measurements. This is a complicated measurement made up of real and imaginary components, which involve resistance and capacitiveness. The resistive path is formed by extracellular fluid while the capacitive component is formed by intracellular liquid. A plasma membrane found between the two fluids plays the role of a dielectric. Inflammation is an automatic response by the body to any injury within soft tissues. An increase in blood flow as well as permeability of blood vessels leads to extravasation. Liquid substances getting into the intracellular space alters the balance of capacitive and resistive pathways. The role of impedance is to look at how a certain material responds to a variety of induced frequencies, with the metrics being phase gain and shift. Stratum corneum, which is the skins outer layer, is made up of densely packed layer of dead cells that possess high electrical resistivity. The skins hydration, thickness, sweat gland density and subsequent activity vary from person to person. Also, these factors are influenced by pathology, something that makes skin resistance to be rather variable. This shortcoming can be done away with by applying certain techniques like skin stripping or application of conductive gels that will neutralize resistance to skin contact. As much as the short-term application of these contact mediums is useful in doing away with skin resistance, they can cause irritation if applied for long periods of time. If capacitive coupling is used, then there is no need to apply contact medium that irritate the skin.

The diabetic foot ulcer sensors system is made up of five separate components. These components are either wireless or wired interfaces, depending on their physical location and function. Figure 1 above shows the application of the Raspberry Pi. It plays the role of the master controller, capturing in-shoe, bioimpendance and environmental measurements. The single-board computer acquires data, controls and formats it, and then records it. The advantages of using this device are that it is readily available, cheap and facilitates ease of connection. Also, it has native python support that makes it possible for the data collection system to be quickly developed and deployed. For the device to be viable and economical in the long term, how much it costs to deploy it can be a significant setback considering the numerous technical problems experienced during its design.

The first step involves collection of data from the environmental monitor, followed by data from the left foot, and then the right foot. This is done inside shoe monitors, with communication between the in-shoe monitors being facilitated by one Bluetooth device. The sought after biological frequencies are less than 1.5Hz, which reflects the heartbeat rate when a person is walking. Bearing this in mind, it is advisable for a sampling frequency of 20Hz to be used in order to facilitate the collection of larger sets of data with the hardware at hand. To match with the Nyquist theorem of sampling, low pass input were used, sampled at 20Hz and filtered at 10Hz. If such a sample frequency is used, it is possible to reproduce any signal that does not exceed 10Hz accurately.

The environmental monitor observed in figure 1 controls event timing while at the same time monitoring environmental humidity and temperature for the test environment. The right and left data collection circuits are controlled by dedicated processors, and are connected to the master controller via Bluetooth. A customized PCB was designed in a way that it offers signal conditioning and connectivity for the sensors. The bioimpendance circuit connected from the in-shoe information collection circuit is used test stand-alone impedance. This software was re-configured in a way that it outputs just the bioimpedance data while at the same time controlling the sample frequency at a figure of 20Hz.

It is also worth looking how the foot-mounted sensor array works. The sensors for humidity, temperature, rotation and acceleration are connected to a micro-USB connector in order to achieve robustness. This connection also facilitates the flexibility needed to re-configure the sensors. Design of the bioimpendance is such that it is like a flexible `printed circuit gotten from electroless copper plating on a PET film. This design makes it possible for sensors to be fitted into the shoe in way that it maintains comfort and flexibility while keeping the costs as low as possible. Sensors for skin temperature, GSR and cost are connected with multi-strand wire to facilitate robustness. The flexible printed circuits are not reliable since their sensor interface is rather fragile.

Sweat and humidity inside the shoe are important factors to consider when monitoring podiatric health of the skin. Both instances of excessively hydrated and dry skin are susceptible to breakdown and risk of infection. A useful metric that can be used to monitor the skins moisture content is GSR, as it can also assist in predicting any future condition. Whether or not sweat evaporates is influenced by humidity, and this may be a significant factor in certain environments.

The diabetic foot ulcer sensor under design is a useful research tool given that it is possible to adapt its positioning. Also, substitute sensors can be used to match the test in question. However, this device should be developed into something that can be worn by a patient at all times in order to...