Research Papers

Design and Fabrication of a Polymeric Microfilter for Medical Applications

[+] Author and Article Information
Rossella Surace

ITIA CNR, Institute of Industrial
Technology and Automation,
via Lembo 38/F,
Bari 70124, Italy
e-mail: rossella.surace@itia.cnr.it

Vincenzo Bellantone

ITIA CNR, Institute of Industrial
Technology and Automation,
via Lembo 38/F,
Bari 70124, Italy
e-mail: vincenzo.bellantone@itia.cnr.it

Gianluca Trotta

ITIA CNR, Institute of Industrial
Technology and Automation,
via Lembo 38/F,
Bari 70124, Italy
e-mail: gianluca.trotta@itia.cnr.it

Vito Basile

ITIA CNR, Institute of Industrial
Technology and Automation,
via Lembo 38/F,
Bari 70124, Italy
e-mail: vito.basile@itia.cnr.it

Francesco Modica

ITIA CNR, Institute of Industrial
Technology and Automation,
via Lembo 38/F,
Bari 70124, Italy
e-mail: francesco.modica@itia.cnr.it

Irene Fassi

ITIA CNR, Institute of Industrial
Technology and Automation,
via Bassini 15,
Milano 20133, Italy
e-mail: irene.fassi@itia.cnr.it

Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MICRO- AND NANO-MANUFACTURING. Manuscript received July 20, 2015; final manuscript received November 16, 2015; published online December 24, 2015. Assoc. Editor: Gracious Ngaile.

J. Micro Nano-Manuf 4(1), 011006 (Dec 24, 2015) (7 pages) Paper No: JMNM-15-1048; doi: 10.1115/1.4032035 History: Received July 20, 2015; Revised November 16, 2015

This paper reports on design, fabrication, and characterization of a microfilter to be used in biomedical applications. The microfilter, with mesh of 80 μm, is fabricated by micro-injection molding process in polymeric material (polyoxymethylene (POM)) using a steel mold manufactured by micro-electrical discharge machining process. The characteristics of the filter are investigated by numerical simulation in order to define a suitable geometry for micro-injection molding. Then, different process configurations of parameters (melt temperature, injection velocity, mold temperature, holding pressure and time, cooling time, pressure limit) are tested in order to obtain the complete part filling via micro-injection molding process preventing any defects. Finally, the component is dimensionally characterized and the process parameters optimized to obtain the maximum filtration capacity.

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Fig. 1

Designed microfilter with diameter 2.3 mm and thickness 0.2 mm (all dimensions in mm)

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Fig. 2

Three-dimensional drawing of mold, insets and polymeric part

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Fig. 3

Contour plot of filling time obtained by simulation of the filling phase

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Fig. 4

Details of part and nominal dimensions of the microfeature

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Fig. 5

Verification of von Mises equivalent stress distribution on the filter (front side)

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Fig. 6

Drawing of inset showing the pins manufactured by micro-EDM. The mold is composed by 76 pins having square section, with a side of 80 μm and height equal to 0.15 mm, with a pin-to-pin distance equal to 70 μm.

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Fig. 10

Confocal image of injected filter manufactured using optimized parameters

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Fig. 11

Most critical samples due to: (a) flash and (b) incomplete filling of ribs in a real and simulated case

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Fig. 13

Contour plot of interaction between mold temperature versus injection speed on the percentage filtering ratio

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Fig. 12

Resulting filtering ratio for each treatment of the three replications for microfilters

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Fig. 9

Examples of defective filters in different process parameters combinations and in order the parameters are Tm (°C), Tmo (°C), Vinj (mm/s), Plim (bar): (a) 230, 100, 150, 1000; (b) 230, 100, 250, 1000; (c) 230, 60, 250, 2000; and (d) 230, 100, 250, 2000

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Fig. 8

Injected filter in POM material

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Fig. 7

Confocal image of inset



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