1. PImMS – An event-triggered time-stamping CMOS Image Sensor for Mass Spectrometry
Andy Clark, Jamie Crooks, Renato Turchetta
STFC Rutherford Appleton Laboratory
Mark Brouard, Ewen Campbell, Jason Lee, Craig Slater, Claire Vallance,
Ed Wilman, Ben Winter, Weihao Yuen
Chemistry, University of Oxford
Jaya John John, Laura Hill, Andrei Nomerotski
Physics, University of Oxford
IWoRID 2011 – Zurich

2. Outline Pixel Imaging Mass Spectrometry = PImMS! PImMS Sensor Overview
Results
Conclusions

3. S atom ion images for OCS photodissociation at 248nm
Imaging Mass Spec
Mass spectrum for human plasma
~ 100 µs
Combines Mass Spectroscopy and Ion Imaging
S atom ion images for OCS photodissociation at 248nm

4. Mass Spectrometry Sample Laser Ionization and Fragmentation Ion Optics
MCP
Phosphor
Screen
Lens
Sensor

5. Proof of Concept
Using fast framing CCD imager (64 x 64, MHz)
: Proof of concept experiment successfully performed on dimethyldisulfide (DMDS) *
CH3S2CH3
Limitations:
System must be pre programmed with target mass flight time
Only 8 masses per measurement
Requires multiple measurement to analyse complex molecules
*: M. Brouard, E.K. Campbell, A.J. Johnsen, C. Vallance, W.H. Yuen, and A. Nomerotski, Rev. Sci. Instrum. 79, , (2008)

6. PImMS Pixel Preamplifier Charge Collection Diodes Shaper Comparator
Mention analogue output and triming
Comparator

7. Ion Intensity Simulations
Important to be sensitive to heavy fragments
Simulated probability to have N hits/pixel
Four buffers allow higher intensity

8. PImMS Pixel
70 µm

9. PImMS 1 Made on the INMAPS process, 180 nm 72 by 72 pixel array
< 50 ns timing resolution
12 bit time stamp storage
4 Memories per pixel
> 1 ms maximum experimental period
Programmable threshold and trim
7.2 mm
5 mm

10. Camera
Cooling system
Option for dry air/nitrogen flushing of sensor chamber
F-mount SLR lens
USB output

11. Optical Testing Quantum Efficiency 8-9% for visible light Max @ 470 nm
Fill factor 20% for front illuminated
Full well capacity 24,000 e-

12. Calibration Each pixel has a 4 bit trim register Maximum trim ~50 mV
Calibration equalizes thresholds for all pixels
Dispersion (sigma) before and after calibration > 3.6 mV

13. Masking Masking allows for sub array selection during calibration
Register in pixel disables comparator
Arbitrary masks are possible

14. Multi Hit Detection

15. Multi Hit Detection
Timecode
Pixel position - y
Pixel position - x

16. PImMS vs PMT

17. Conventional CCD Image
Spatial Imaging
Conventional CCD Image
PImMS Image

18. PImMS 2 Larger Array 324 by 324 pixels 23 mm by 23 mm active area
380 Experiments/sec
Potential 400,000 measurements per experimental cycle
Designed to also work directly after MCP

19. PImMS 2 Larger array Improved power supply and reference routing
Increased on-chip control
On-chip bias and reference generation
Serial output
Extended output bandwidth
Reduced pin count for vacuum applications
Schedule:
Submission this September
Testing at the end of the year

20. Summary
Spatial resolution can be used to map a surface (increasing throughput) or to perform velocity mapping providing structural information
CMOS and INMAPS enable effective imaging at more than 20 million frames per second!
Multiple memories allow simultaneous capture of different mass peaks
The PImMS sensor has been proven to operate within the TOF MS system with timing resolution of < 50 ns
Second generation sensor will be ready at the beginning of 2012
Other applications, ex. atom probe tomography, fluorescent imaging etc

21. Questions?

22. Applications
Parallel processing – High throughput sampling

23. Applications Surface imaging for separate mass peaks
Replace scanning with wide-field imaging
R.Heeren et al

24. Fingerprinting of molecules
Applications
Fingerprinting of molecules
mass fingerprinting of human serum albumin (from Wikipedia)