Laser microfabrication of long thin holes on biodegradable polymer in vacuum for preventing clogginess and its application to blood collection

Abstract

The present paper investigates the excimer laser microfabrication of long thin holes on biodegradable polymer material (polylactic acid, referred to herein as PLA). The fabrication was carried out on several kinds of polymers in the atmosphere. In the case of PLA, a phenomenon was observed after fabrication whereby the inside of the hole is clogged at several points by ablated material and residual gas. Analysis of chemical components of the ablated products was performed using a gas chromatography–mass spectrometer (GC/MS). They are proved to be intermediate products of ester compound and lactide, and their oxides, which indicates that the clogging phenomenon is partially caused by the hydrolysis reaction based on the biodegradable characteristics of PLA. The fabrication was carried out in vacuum and nitrogen gas. The clogging tendency was eliminated in vacuum, whereas it was not eliminated in nitrogen gas, which indicates that the ablated residues are evaporated by lowering the ambient pressure below their vapor pressure, proving the effectiveness of the fabrication in vacuum for preventing the clogginess. The effect of existence of oxygen in the ambient atmosphere on the laser fabrication rate was also investigated, proving that auto-oxidation reactions urge the decomposition of polymer. The fabricated long thin hole on PLA was applied to blood collection.