Packaging for microfluidic devices and systems

Zhen YANG^*# and Ryutaro MAEDA^*

* Institute of Mechanical System Engineering, AIST(Namiki 1-2, Tsukuba 305-8564)

# NEDO Fellow

  

マイクロ流体デバイス及びシステムの実装技術

楊振^*#，　前田龍太郎^*

*産業技術総合研究所機械システム研究部門（〒305-8564 つくば市並木1-2）

# NEDOフェロー（Zhen.YANG@aist.go.jp）

概要

マイクロ流体デバイスはバイオ、化学分析と合成等への応用が期待され、関連する研究が現在盛んに行われている。新しい材料の採用や、マイクロポンプ等各機能デバイスの性能向上が進み、システム化や商品化の段階に達している。実装技術は全体のシステム化にとって各デバイスの設計、製造及び計測技術と同等以上に重要であるが、技術的な困難さの割に学術色が薄いためか、報告例が少ない。本稿ではマイクロ流体システムにおける実装技術の重要性と技術的課題についてまとめ、個別の要素技術やデバイス単体、モジュール、試験用及びシステムレベルのいくつかの事例を紹介する。更に、これらの実装研究開発が今後進むべき方向についても述べる。

1. Introduction

With the development of micro electro mechanical systems (MEMS), it is called micromachine in Japan, microfluidic application has become one of the hot fields since 1990s. The reason for the continuous interest in this field is its obvious applications. There are the needs from biological, pharmaceutical and medical applications covering both diagnosis and clinical treatments. The needs are also from chemical analysis and chemical synthesis. The applications in space technologies and semiconductor fabrication are also very interesting. Ink jet printing technologies have already obtained extreme success in both civil and industrial applications.

Until now, research activities focused on developments of various functional devices, methods for creating networks of microchannels are well established on silicon, glass and polymeric substrates using etching or molding processes. PZT-actuated micropumps and micromixers have achieved excellent performance. Various microsensors have been reported. As commercialization of MEMS and microsystems has gained momentum, product packaging has gained increasing attention from the industrial and research communities. Packaging has been major stumbling blocks in capitalizing the full market potential of micro engineering products. The packaging technology breakthroughs are a critical element for continuous growth of microfluidic researches and applications in the next decade.

 The success of microfluidic researches and extension to commercial products depend on deliver the innovations in the following key technologies.

l     Design

l     Fabrication

l     Packaging

l     Testing

We focus on the packaging technologies in this paper.

2. The importance of packaging technology

   (1) System consideration

   (2) Reliability consideration

   (3) Miniaturization consideration

   (4) Cost consideration

3. The challenges in packaging fluidic MEMS 

MEMS packaging has some commons with microelectronics packaging. Learning their technologies and methodologies is very important to MEMS packaging.

(1) Microelectronics packaging should consider about

    Fixity: 

    Electrical Input and Output (I/O): 

    Protection from all possible attacks 

    Thermal consideration: 

(2) Fluidic MEMS packaging increased the complexity. It might consider about

Everything required for microelectronics packaging

Isolation from physical dumping and maintenance of reference pressure

   I/O of working fluids: 

   The I/O of working fluids in micro scale.

4. Practical developments in packaging fluidic MEMS

   4.1 Packaging working fluids into a closed reservoir

   4.2 New material for bonding

   4.3 Disposable fluidic chips for biological applications

   4.4 TO can

   4.5 World-to-chip socket for microfluidic prototype development

   4.6 Module level packaging

   4.7 System level packaging

5. Basic conceptual consideration on I/O

   (1) I/O for energy

   (2) I/O for information

   (3) I/O for materials

6. Strategies for further development

   6.1 Start from packaging functional device individually

   6.2 Package assembly

   6.3 Concurrent design 

   6.4 Sharing the developed knowledge and problems

Reference

1)     T.R. Hsu: “MEMS demand new package designs”, Electron. Packag. Prod., vol.41, pp52-54, 2001.

2)     M. Esashi, S. Sugiyama, K. Ikeda, Y. Wang and H. Miyashita: “Vacuum-Sealed Silicon Micromachined Pressure Sensors”, Proceedings of the IEEE, Vol.86, pp.1627- 1639, 1998

3)     Z. Yang, H. Suzuki, S. Sasaki and I. Karube: “Fabrication of Oxygen Electrode Arrays and Their Incorporation into Sensors for Biochemical Oxygen Demand”. Anal. Chim. Acta. Vol. 357: pp41-49, 1997

4)     A. Han, K.W. Oh, S. Bhansali, H.T. Henderson and C.H. Ahn: “A low temperature biochemically compatible bonding technique using fluoropolymers for biochemical microfluidic systems”, MEMS2000, Miyazaki, Japan, pp 414-418.

5)     http://www.agc.co.jp/english/chemicals/shinsei/cytop/cytop.htm

6)     http://www.calipertech.com/technologies/fabrication.html

7)     http://www.redwoodmicro.com/nc15002.htm

8)     http://redwoodmicro.com/Papers/

9)     K. Gilleo: “MEMS Packaging Solutions Open New Markets”, Electron. Packag. Prod., June, 1, 2000

10) http://www.camcon.co.uk/PDFs/InterfacePDFs/microengineering.pdf

11) T.J. Yao, S. Lee, W. Fang and Y.C. Tai: “Micromachined Rubber O-ring Micro-Fluidic Couplers,” MEMS2000, Miyazaki, Japan, pp. 624-627, 2000

Acknowledgements

The authors wish to thank Dr. Sohei Matsumoto for his valuable suggestions and fruitful discussions and Tomoko Imai for her help in graphic works.

Legends

Fig. 1. A polymer based disposable bio-chip for automatic sample preparation and analysis [6].

Fig. 2. A microvalve die in TO can packaging [7].

Fig. 3. A socket mounted with a 5-micromixer array chip. The volume of each mixing chamber is 0.7 μl and the pitch of silicone tube is 2.5 mm. See text for detail.

Fig. 4. Top (left) and back (right) view of the socket. See text for detail. On the top of the socket, springs in pitch of 1.27 mm were arranged for electrical connection with die. On the back of the socket, pins in pitch of 2.54 mm were arranged for electrical connection to the outside.

Fig. 5. Backside view of a (8+1)-micromixer array chip. Electrical lead pads formed directly on silicon substrate to connect with piezo-ceramic actuators. The chip is Si/glass structure in the size of 29.1 mm x 27.5 mm x 0.9 mm.

Fig. 6. Structure of a silicon based mass flow controller module [8]

Fig. 7. A bubble jet printing head (HP 51645G) using flexible tape for electrical connection. Ink jet nozzle arrays are also formed on the tape.

Fig. 8. A piezo-actuated plastic micropump (Institute for microtechnology, Germany). The electric and working fluid connection are arranged in a planar way [10].

Fig. 9. A microfluidic device with o-ring coupler is plugger into a microfluidic board [11].