The Study And Design Of Portable Glucose Monitoring

With the quickening social pace and the great improvement of people’s livingstandard, many people become not to follow the right daily routine and not to attachimportance to a healthy diet. At a result, diabetes has been spreading among thesepeople. Diabetes is a disease that too much glucose in one’s blood, which can causedamage to human tissue or even reduce the lifetime. However, diabetes can be treatedthrough insulin injections, healthy diet and normal daily routine. So it becomesimportant to detect the glucose content of the blood and take the right treatmentmethod, for the purpose of keeping fit.The detectors on sale for detecting glucose content of blood mostly base onelectrochemical method or optical refractometry method. Detectors base onelectrochemical method with the advantages of inexpensive, insensitive to the outsidenoise and good stability, is gradually replacing others. Furthermore, theelectrochemical glucose sensor is divided into enzymatic glucose sensor andnon-enzymatic glucose sensor. And most of the sensors of the detectors on sale arebased on One-Time enzymatic glucose sensor. However, our design chose thenon-enzymatic glucose sensor that made by ourselves as the sensor of the detector，which could be used repeatedly. When electrochemical reaction happen, it cangenerare the current as small as0.08uA. Better stability, less insensitive to the outsidenoise and much more cheap are its advantages. To take advantage of this sensor, wedesign our detector of portable, versatile, low power consumption and faster.The working electrode of the sensor is made by ITO glass that is covered byMOS nanotubes, which are prepared by the method of electrospinning fabrication.And three-electrode electrochemical testing principle is the detection principle. Nowwe introduce our design through the hardware design and the software design.Hardware is the basic of all testing equipment. STM32F103microprocessorwas chose as the center of hardware. It playing the role of controlling the ADC,processing digital signal, receiving input signal from the keyboard, driving the LCD and controlling the interface circuit of the sensor. The interface circuit is thepotentiostat. OPA124was chose to design a negative feedback circuit to achieve thepurpose of potentiostat designing. OPA124is a operational amplifier with theadvantages of high-precision, low noise and high input impedance. After that, wedesigned the current to voltage circuit, amplifier circuit, low-pass filter circuit and theadjustment circuit. All the gain resistors in these circuit are precision metal filmresistors and all the conducting wires that conduct the weak current are coaxial cablesaim at preventing noise from affecting the circuit.Good software design could activate the detector. Low level driver and highlevel driver are the two steps of the software design. Low level driver mainly refers tothe initialization of ADC, additional FLASH memory, RTC and LCD. After that, highlevel driver include developing all the functions of the detector and controlling LCDto display the functions for the users in the system of μC/GUI. Displaying the glucosecontent of the blood, historical test results and analysis of the historical results are thefunctions of the LCD. However, the most important tasks for the software design areto optimize the digital signal and convert the voltage signal into glucose contentsignal. Kalman filter and interpolation were took to solve the two tasks.We had detected many different glucose content and had summarized thefunction of glucose content and voltage signal after the design of hardware andsoftware were finished. Because the principle of glucose monitoring is three-electrodeelectrochemical testing principle, all of our design methods could be learnt by manydesigners to develop all kind of detectors. For instance, detectors of pollutants inwater such as nitrogen, phosphorus, mercury and cadmium; Detectors of toxic gasessuch as hydrogen sulfide, carbon monoxide and formaldehyde.