HARRICK PLASMA

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BASIC PLASMA CLEANER

PDC-32G

Our Basic Plasma Cleaner is a compact, inexpensive tabletop plasma instrument with a hinged door, viewing window, and fine control metering valve, suitable for nanoscale surface cleaning and activation of small samples.

- 가장 작은 사이즈, 탁상형모델

- RF 파워 조절가능

(Low, Medium, and High power settings)

- RF 파워 최고출력 : 18W

- 챔버사이즈 : 3" x 6.5" 인치 사이즈

- 고정 챔버커버에 윈도우 장착

- 팬쿨러 장착

- 1/8" NPT metering 벨브로 다양한 가스 주입 및 컨트롤이 가능

(PLASMAFLO 악세서리 구입시)

더 자세히

What is Plasma?

Plasma, the fourth state of matter, is a distinct processing medium for surface treatment and surface modification. This note discusses the nature of plasma and how plasma is formed, its unique advantages, and the types of surface interactions that are possible during plasma treatment.

자세히

PDMS BONDING (MICROFLUIDICS)

Poly(dimethylsiloxane) (PDMS) is a silcone-based organic polymer used extensively in professional and academic research laboratories for its low cost and high versatility. PDMS is inert, transparent and easily customized via soft lithography, a technique used to mold PDMS and imprint nano-scale features and microchannels into its surface. Harrick Plasma Cleaners remove organic contamination and activate the PDMS surface in preparation for bonding with glass, PDMS or other similarly treated surfaces. PDMS bonding is most commonly used in the development of microfludic devices. For references citing the use of our plasma cleaners in microfluidic applications, see the Microfluidic Devices category in our Technical Library.

SURFACE HYDROPHILICITY

Plasma treatment introduces polar functional groups that increase the wettability of a substrate. Increased surface wettability enhances fluid flow within microfludic devices and improves PDMS biocompatability.

Immediately following plasma treatment, the PDMS surface begins to undergo hydrophobic recovery as the high energy surface reconfigures towards a lower energy state. It is recommended that PDMS bonding and other subsequent processing steps be performed within 15 minutes to an hour of plasma treatment.

Additionally, alternating hydrophilic-hydrophobic regions may be patterned on microfluidic surfaces by plasma treating devices through a patterned mask.

PROCESSING METHODS

Below are suggested process conditions for plasma activation of PDMS-PDMS or PDMS-glass in a Harrick Plasma cleaner (some experimentation may be required to determine optimal process conditions):

Use oxygen (O2) or room air as the process gas
Pressure: 200 mTorr to 1 Torr
RF power: Typically HIGH
Process time: 15-60 seconds
As is the case with experimental processes and fabrication techniques, plasma process conditions reported by users have varied widely, even when plasma treating similar PDMS materials.

ADDITIONAL PROCESS CONSIDERATIONS

After Plasma Treatment, press and hold PDMS components together lightly for 30 sesonds. Do not pull apart and adjust alignment as this will disrupt bond formation. Pressing with too much force may collapse microfluidic channels.
Heat the assembled device at 80-100 degrees Celsius for 60 seconds in an oven or hot plate. The high temperature provides activation energy for additional bond formation.
Cleanliness: the presence of particulates or oil can block bonds from forming. Avoid touching the surfaces to be bonded when removing PDMS from the plasma chamber
Surface Roughness: Smooth surfaces maximize contatct between bonding materials, providing more opportunity for siloxane bond formation. Adjust your soft lithography process to ensure smooth substrates.
Air vs Oxygen: Oxygen is more efficient than air due to the higher concentration of reactive oxygen species. Additionally, air from an environment prone to daily fluctuations in humidity or particulates can adversly affect PDMS bonding.
Plasma treatment should not exceed 2 min, as prolonged plasma exposure causes cracking in PDMS and migration of low molecular mass molecules from bulk to surface, decreasing the number of hydrophilic SiOH groups and resulting in weak or incomplete bonding
Oxidized surfaces should be brought into contact immediately after plasma treatment to achieve strongest bond possible
PDMS surface recovers hydrophobic properties (aging) with time after plasma treatment (~1 hour).