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New Perspectives in Biosensors Technology and Applications Part 2

Tham khảo tài liệu 'new perspectives in biosensors technology and applications part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 22 New Perspectives in Biosensors Technology and Applications Fig. 20. Photo of the MEMS Faraday cup Fig. 21. Photos of the MEMS Faraday cup packaged 5.4 Testing of the micro Faraday cup For the MEMS Faraday cup chip packaged with PCB a base should be fabricated to realise a reliable connection between the MEMS Faraday cup and the ion source. The base is made of red copper which can effectively shield the noise from the environment. The photos of the red copper shielding base assembled MEMS Faraday cup and the ion source are shown in figure 21. In order to test the performance of the MEMS Faraday cup the chip is tested with KEITHLEY237. In this experiment the carrier gas is nitrogen gas and the sample is acetone the concentration of which is about 100ppm. The experimental system is shown in figure 22. 2 3 1 N2 2 Flowmeter 3 UV ion source and sample cell 4 Micro-FCA 5 Electrometer Fig. 22. Experimental apparatus of the MEMS Faraday cup FAIMS Detection Technology Based on MEMS 23 1 Ion collection experiment with the MEMS Faraday cup In the experimental system of figure 22 the carrier gas flow is adjusted to 100L h. We make the comparison of the ion collection results among the chips of the MEMS Faraday cup with different structural parameters. Through comparison of the signal the absorption efficiency of the MEMS Faraday cup with different structural parameters is evaluated. Figure 23 shows a typical ion signal curve collected by the MEMS Faraday cup. This means that the signal of the MEMS Faraday cup is stable which can work in the atmospheric environment and is completely capable of detect ion. 1.50E-010- 05 .2 1.00E-010- Ơ 5.00E-011 - 0.00E 000 -I------- ------1-------- ----1---------- -------1------ ------1 0 50 100 150 200 Sampling points Fig. 23. Ion signal curve received by the MEMS Faraday cup -2.00E-013-I-1----1---1----1---- -----1--1---1-----1----1 0 10 20 30 40 50 Sampling Points Fig. 24. Noise in the body of KEITHLEY 2 Anti-interference experiment Shut .