SiM20 Posters

27 Sensors in Medicine 2020 H IGH -P RECISION B IOMAGNETIC M EASUREMENT S YSTEM B ASED ON TMR E FFECT The readout circuit is so small with only 4 parts, amplifier, filter, Analog-digital converter (ADC) and microprocessor. The structure of the TMR sensor is equivalent to ‘Wheatstone Bridge’ circuit, which suppresses the offset at the output of TMR sensor. A transimpedance amplifier (TIA) will amplify the tiny current and transfer it into a measurable voltage signal. However, the noise is also amplified by TIA, a low-pass filter is needed to filter the noise from the TIA. Because the current signal output from TMR sensor is a direct current (DC) signal, the filter part in our design can decrease the influence of all alternating current (AC) signals. An ADC is placed after filtering, a microprocessor is used to process and display the final direct current (DC) signal. Figure 3. A processing chain of the portable magnetic-assisted malaria diagnosis system. E XECUTION & E XPERIMENTAL R ESULTS 0.0 0.1 0.2 0.3 0.4 0.5 0.6 319.8 320.6 321.4 322.2 323.0 323.8 Output Voltage [mV] Time [s] 0.0 0.1 0.2 0.3 0.4 0.5 0.6 320.2 320.6 321.0 321.4 321.8 322.2 Output Voltage [mV] Time [s] 0.0 0.1 0.2 0.3 0.4 0.5 0.6 319.4 319.8 320.2 320.6 321.0 321.4 Output Voltage [mV] Time [s] 0.0 0.1 0.2 0.3 0.4 0.5 0.6 319.6 320.0 320.4 320.8 Output Voltage [mV] Time [s] 0.0 0.1 0.2 0.3 0.4 0.5 0.6 319.2 319.6 320.0 320.4 320.8 Output Voltage [mV] Time [s] 0.0 0.1 0.2 0.3 0.4 0.5 0.6 319.4 319.8 320.2 320.6 321.0 321.4 Output Voltage [mV] Time [s] Sample 1 Sample 2 Sample 1 Sample 2 Sample 1 Sample 2 (a) (b) (c) (d) (e) (f) Figure 4. Portable Halbach Cylinder: (a) Produced magnetic fields along the y axis (-15mm to 15mm); (b) Experimental photo. Figure 5. Measurement results of the proposed TMR-based system with real Malaria samples: (a-c) sample 1 & (d-f) sample 2. C ONCLUSION AND FUTURE WORK In this project, we design and develop a miniaturized and handheld on-chip magnetoresistive-based device for a rapid label- free diagnosis of malaria. The device consists of four major components; (i) Tunnelling magnetoresistance (TMR) sensor; (ii) Halbach array of magnets (iii) Analog front end (AFE); (iv) LabVIEW interface. The system includes sensory and electronic boards to collect the data, cancel the noise, amplify and to transfer them to be displayed. A LabVIEW interface, as a display module, is utilized to display detected voltage signal by sensor due to the malaria pigment. [1] S. Zuo, K. Nazarpour and H. Heidari, 27th IEEE International Conference on Electronics, Circuits and Systems (ICECS), Glasgow, 2020. [2] Z. Yin, E. Bonizzoni and H. Heidari, IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology, September 2018. www.melabresearch.com University of Glasgow, charity number SC004401