Cause: Research Papers Examples

The type of hardware used in a glucometer.

A glucometer (glucose meter) is a medical technology device used measure glucose concentration in a given solution. The units of measurement used vary by region and they are milligram per deciliter (mg/dl) and millimole per liter (mmol/L). Glucometers are critical elements in Home Blood Glucose Monitoring (HBGM) devices used by diabetics who suffer from Type 1 and Type 2 Diabetes Mellitus. HBGM devices are used to monitor blood sugar levels on a daily basis with multiple measurements taken in a single day (Dalvi).
The glucometer hardware described in this paper is based on designs by Freescale Semiconductor Company. The amount of glucose content in blood has a huge effect on its electrical conductivity, and this serves as the underlying principle of determining glucose concentration in a blood sample. This biological phenomenon is practically modeled in an electrical circuit where a variable resistor is connected in series to another resistor that has a fixed voltage source. In this case, a voltage drop in the variable resistance is determined by conductivity of the resistance. High conductivity means a low voltage drop while low conductivity implies a high voltage drop. These variations can be analyzed using a Micro Processing Unit (MPU) which determines the concentration of glucose and displays it on a Liquid Crystal Display (LCD) (Freescale).
The functionality of this glucometer can be extended to allow for both wired and wireless communication with devices such as calorimeters, insulin dispensers, and smartphones. This functionality can be used for remote patient monitoring and telehealth applications (Freescale).

The Glucometer and Test strip hardware and operation:

The test strip is made of an electrode with chemical elements where the blood test sample is deposited. The elements in the test strip trigger a reaction that generates and electric current. The current is passed through a trans-impedance amplifier that converts it into an output voltage that is proportional to the input current. Freescale offers two models of the glucometers i.e. Kinetis K50 and Flexis MM MCU. The Figure 1 (a) below shows the basic block diagram of a blood glucometer complete with MPU, input and wireless communication (Freescale).
Figure 1 (b) show the equivalent simplified circuit where the resistance voltage (RV) equals blood conductivity.
Figure 1 (a) General Blood Glucose Monitor/Meter Block Diagram, and (b) is the equivalent circuit where Rv is Equal to Conductivity of Blood (Source: Freescale).
The trans-impedance amplifiers embedded in these models allow the user to capture the current generated by the chemical reaction of glucose with the enzymes on the strip. The external hardware components used help in configuring the amplifiers desired gain value. The TriampV1 trans-impedance module is managed using values from the TIAMPCO MPU register. The TIAMPEN bit of the register is responsible for enabling the trans-impedance module while the LPEN bit is for power management. When the state is LPEN=0, the module is in high-speed mode, and when LPEN=1, the low power mode is enabled. The low power mode is used to conserve power in battery-dependent systems, but it also compromises the system's response speed. The TriampV1 module has a TRIOUT pin which must be connected using an external gain resistor to the VINN pin that inverts the operational amplifier’s input. The VINP pin is grounded.

The Figure 2 below shows the basic circuit for a tans-impedance amplifier.

Figure 2 Basic trans-impedance amplifier circuit
The enzymatic strip in the glucometer is the main sensor since it detects hydrogen peroxide produced during enzyme catalyzed glucose oxidation. The chemical word equation for the reaction is shown below with the subsequent chemical reaction.
GlucoseGlucose Oxidase Enzyme gluconolactone+Hydrogen Peroxide
C6H12O6Glucose Oxidase EnzymeC6H10O6+H2O2
The strips used are amperometric with a three-electrode design. The design is especially helpful when amperometric sensors are used since it improves the reliability of current and voltage measurements taken from the same chemical reaction. The three electrode setup consists of a counter electrode (CE), working electrode (WE), and reference electrode (RE). The Figure 3 below show the working of a Flexis MM glucometer with test strip inserted (Freescale).
Figure 3 Basic Block diagram showing the working of the Flexis MM glucometer with test strip.
Other components such as Microprocessor Units (MPUs), (Analog-to-Digital Converters) ADC, Digital-to-Analog Converters, wireless communication adapters, and the LCD screen are secondary features used for computation, signal processing, communication and displaying output. These vary according to the vendors, but basic working of the test strip and trans-impedance amplifier is almost general across most vendors.

Other types of Glucometer hardware.

As the technology evolves to smart devices with different integrated functions, glucometer technologies are also advancing. A good example is Dario, a new glucometer that can be connected to a smartphone. The glucometer is small (about the size of cigarette lighter), and it turns a smartphone into a fully integrated glucose meter (Hoskins). The novel technology comprises of a smartphone application for interfacing with the device, test strips, and a lancet poker. It connects to the smartphone via the audio jack and once the application launches, the user can monitor his blood glucose levels, analyze them graphically, and perform all manner of allowed monitoring and analysis functions (Aviad).
A similar technology to Dario is the iBGStar blood glucose meter and monitoring system that is compatible with Apple products such as the iPhone 4S/5/5C/5S/6/6 Plus, and the iPod touch 5 and it interfaces with these devices using the original 30-pin Apple Lightning™ Adapter which is separately sold. The device works by first running the iBGStar Diabetes Manager app, attaching the Adapter to the Apple device, and finally linking the iBGStar device to the adapter. The operating system requirements for the iBGStar app is Apple’s iOS 5 and higher versions (iBGStar).

Works Cited:

Aviad, Michael. 'Dario: Turning Your Smartphone into an All-In-One Glucose Meter'. A Sweet Life. N.p., 2012. Web. 14 Mar. 2015.
Dalvi, Namrata. Glucose Meter Reference Design. 1st ed. Microchip Technology Inc., 2013. Web. 14 Mar. 2015.
Freescale,. Medical Applications User Guide. 1st ed. Freescale Semiconductor, 2014. Web. 14 Mar. 2015.
Hoskins, Mike. 'Dario Turning Your Smartphone Into A Glucose Meter'. Healthline.com. N.p., 2013. Web. 14 Mar. 2015.
IBGStar,. 'Learn More About The IBGStar Blood Glucose Meter, Compatible With IPhone. ibgstar. N.p., 2015. Web. 14 Mar. 2015.