1. Four Channels Data Acquisition System for Silicon Photomultipliers Mateusz Baszczyk, Piotr Dorosz, Sebastian Głąb, Wojciech Kucewicz, Łukasz Mik, Maria Sapor Department of Electronics, AGH – University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow, Poland e-mail kucewicz@agh.edu.pl sglab@agh.edu.pl

2. Agenda Fluorescence; Silicon Photomultiplier description; Description of previous measurement system; Four channel data acquisition system; Results; Summary; Future work. 2

3. Why do we measure fluorescence light intensity? Dye-labelled cells can be count by fluorescence light intensity measurement; At low concentrations the fluorescence intensity is generally proportional to the concentrations of fluorophore. 3

4. Fluorescein and Bio-Tek filters spectra fluorescein resorufin 4

5. Optical block 5

6. Silicon Photomultiplier The idea appears in the late 90-ties: „Photon Detection with High Gain Avalanche Photodiode Arrays” S. Vasile, P. Gothoskar, R. Farrell, D. Sdrulla „Silicon avalanche photodiodes on the base of metal-resistor- semiconductor (MRS) structures” V. Saveliev, V. Golovin 6

7. Structure 7

8. Current - Voltage Characteristic 8

9. Photodiode Operation Mode 1 photon generates 1 electron-hole pair 9

10. Avalanche Operation Mode 1 photon generates 10-200 electron-hole pairs 10

11. Geiger Operation Mode 1 photon generates 10 5 - 10 6 electron-hole pairs 11

12. Typical SiPM Parameters sensL s1020Hamamatsu S10362- 11-025C Spectral Range ( λ) 400-1100 nm320-900 nm Peak Spectral Response ( λ) 490 nm440 nm Breakdown Voltage (Vbr)28.6 V--- Operating Voltage (V)30.6 V70.82 V Microcell Gain10 6 2.75 · 10 5 SPM Pixel Active Area Φ 1 mm Number of Pixels4001600 Dark Rate (MHz)0.420.3 12

13. Previous Measurement System For Fluorescence Picosecond 2600C generator Cuvette holder with specimen GPA amplifier QDC device PC with Labview application excitation filter emission filter Agilent 33250 generator trigger signal gate pulses 13

14. First Measurement System For Fluorescence 14

15. Acquisition System 15

16. Acquisition System 16

17. Front-end ASIC 17

18. Front-end ASIC 18

19. Front-end ASIC 19

20. Linearity – high gain 20

21. Linearity – low gain 21

22. Measurement results 22

23. Measurement results 23

24. Measurement results 24

25. Measurement results 25

26. Measurement results 26

27. Measurement results 27

28. Light Intensity 28

29. Light Intensity 29

30. Light Intensity 30

31. Without Coincidence 31

32. Coincidence 32

33. Results of fluorescence light measurements 976.6 [pg/ml] 61.05 [pg/ml] y = -572500 x² + 223.6 x + 6458000 – fluorescein y = -373800 x² + 170.3 x + 14030000 – resorufin 33

34. Influence of Temperature and Bias 34

35. Dark Current Rate 35

36. Influence of Temperature and Bias 36

37. Conclusions We have designed, built and optimized readout system for detection of single photons; We have tested readout circuit with light and confirmed that it is linear; We can distinguish a dozen or so photons and eliminate thermal generation from measurement data; System with silicon photomultiplier has a good sensitivity and can be used to measure fluorescence light intensity for fluorescein concentration from 1ug/ml to about 60pg/ml and resorufin at the level of 1ng/ml up to 1ug/ml. 37

38. Future work Stabilization system compensating temperature influence on SiPM gain by varying supply voltage; Measurements of fluorescent dyes in microbioreactors. scanning probe micro-bioreactor 38

39. Thank you for your attention 39