A compact, low-cost microliter-range liquid dispenser based on expandable microspheres

Roxhed, Niclas; Rydholm, Susanna; Samel, Björn; Wijngaart, Wouter van der; Griss, P.; Stemme, G.

doi:10.1088/0960-1317/16/12/030

Cited by 15 publications

(13 citation statements)

References 18 publications

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“…Integrated with a simple liquid propulsion mechanism, a patch-like system can be designed where the seals break once the device is actuated. An example of such an actuator capable of generating pressures above 100 kPa was previously introduced by us (Roxhed et al 2006), and demonstrated in use with non-sealed microneedles for insulin delivery in vivo (Nordquist et al 2007).…”

Section: Discussionmentioning

confidence: 99%

Membrane-sealed hollow microneedles and related administration schemes for transdermal drug delivery

Roxhed

Griss

Stemme

2007

Biomed Microdevices

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This paper presents fabrication and testing of membrane-sealed hollow microneedles. This novel concept offers the possibility of a sealed microneedle-based transdermal drug delivery system in which the drug is stored and protected from the environment. Sealed microneedles were fabricated by covering the tip openings of out-of-plane silicon microneedles with thin gold membranes. In this way a leak-tight seal was established which hinders both contamination and evaporation. To allow drug release from the microneedles, three different methods of opening the seals were investigated: burst opening by means of pressure; opening by applying a small voltage in the presence of physiological saline; and opening as a result of microneedle insertion into the skin. It was found that a 170 nm thick gold membrane can withstand a pressure of approximately 120 kPa. At higher pressures the membranes burst and the microneedles are opened up. The membranes can also be electrochemically dissolved within 2 min in saline conditions similar to interstitial fluid present in the skin. Moreover, through in vivo tests, it was demonstrated that 170 nm thick membranes break when the microneedles were inserted into skin tissue. The proposed concept was demonstrated as a feasible option for sealing hollow microneedles. This enables the realization of a closed-package transdermal drug delivery system based on microneedles.

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Section: Discussionmentioning

confidence: 99%

Membrane-sealed hollow microneedles and related administration schemes for transdermal drug delivery

Roxhed

Griss

Stemme

2007

Biomed Microdevices

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“…The automotive industry use microspheres in underbody coatings, tires, composite materials, and for adhesive debonding 9–12. Interesting new applications of microspheres are as single‐use pumps or valves in microfluidic systems13, 14 or as sacrificial templates in the production of foamed ceramics 15, 16…”

Section: Introductionmentioning

confidence: 99%

“…8 The automotive industry use microspheres in underbody coatings, tires, composite materials, and for adhesive debonding. [9][10][11][12] Interesting new applications of microspheres are as singleuse pumps or valves in microfluidic systems 13,14 or as sacrificial templates in the production of foamed ceramics. 15,16 The expansion temperature, particle size, maximum expansion, and the microsphere surface chemistry are all important parameters when choosing the appropriate microsphere grade.…”

Section: Introductionmentioning

confidence: 99%

Thermally expandable microspheres with excellent expansion characteristics at high temperature

Jonsson

Nordin²,

Kron³

et al. 2010

J of Applied Polymer Sci

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Thermally expandable core/shell particles with a poly(acrylonitrile-co-methacrylonitrile) shell and a hydrocarbon core (blowing agent) have been prepared by suspension polymerization. The objective of this study was to gain a deeper understanding of the parameters determining the expansion properties of these microspheres. It was found that the amount, the boiling point, and the structure of the blowing agent are important parameters for the expansion properties. For example, a higher maximum expansion was reached when using bulkier blowing agents and thus a lower diffusion rate through the polymer shell. Further, the amount and structure of the crosslinker were also found to be essential for the expansion properties. For this particular system, it was found that a dimethacrylate-functional crosslinker gave significantly better expansion when compared with diacrylate-or divinylether-based crosslinkers. Beside these parameters, it was also observed that the particle-size distribution influence the expansion properties of the microspheres. V C

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“…This transition is essentially irreversible. Once the sphere is cooled, it remains in its expanded state (Roxhed et al 2006;Griss et al 2002).…”

Section: Thermo-responsive Pdms Valvesmentioning

confidence: 99%

A disposable, integrated loop-mediated isothermal amplification cassette with thermally actuated valves

Liu

Mauk

Bau

2011

Microfluid Nanofluid

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An inexpensive, disposable, integrated, polymer-based cassette for loop-mediated isothermal amplification (LAMP) of target nucleic acids was designed, fabricated, and tested. The LAMP chamber was equipped with single-use, thermally actuated valves made with a composite consisting of a mixture of PDMS and expandable microspheres. The effect of the composite composition on its expansion was investigated, and the valve's performance was evaluated. In its closed state, the valve can hold pressures as high as 200 kPa without any significant leakage. Both the LAMP chamber and the valves were actuated with thin film heaters. The utility of the cassette was demonstrated by carrying out LAMP of Escherichia coli DNA target and reverse transcribed loop meditated isothermal amplification (RT-LAMP) of RNA targets. The amplicons were detected in real time with a portable, compact detector. The system was capable of detecting as few as 10 target molecules per sample in well under 1 h. The portable, integrated cassette system described here is particularly suited for applications at the point of care and in resource-poor countries, where funds and trained personnel are in short supply.

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A compact, low-cost microliter-range liquid dispenser based on expandable microspheres

Cited by 15 publications

References 18 publications

Membrane-sealed hollow microneedles and related administration schemes for transdermal drug delivery

Membrane-sealed hollow microneedles and related administration schemes for transdermal drug delivery

Thermally expandable microspheres with excellent expansion characteristics at high temperature

A disposable, integrated loop-mediated isothermal amplification cassette with thermally actuated valves

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