Electroactive polymer membranes as substrates for for point-of-care devices Ricardo Brito-Pereita 1,2,3 , André S. Macedo 1,3 , Senentxu Lanceros-Méndez 1,4,5 , Vanessa F. Cardoso 1,2 1 CF-UM-UP, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal 2 CMEMS-UMinho, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal 3 IB-S, University of Minho, 4710-057 Braga, Portugal 4 BCMaterials, UPV/EHU Science Park, 48940 Leioa, Spain 5 IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain; ABSTRACT Point-of-care devices (POC) are becoming essential for medical assistance in emergency situations or location with difficult access to medical infrastructures. In this work, innovative microfluidic substrates based on electroactive poly(vinylidene-co-trifluorethylene)-P(VDF-TrFE) with tuned morphologies and adequate physicochemical properties were developed using electrospinning and phase inversion techniques, as alternative to commercially available two-dimensional microfluidic substrates based mainly on cellulose. Their hydrophilicity was tuned using plasma treatments and barriers were implemented using wax printing to fabricate a design able to carry out glucose assays as a proof of concept. KEYWORDS: Point-of-care, μPAD, P(VDF-TrFE), Electrospinning, Phase inversion, Wax-printing. INTRODUCTION Microfluidic paper-based analytical devices (μPADs) are a suitable option for simple, fast and portable devices for medical diagnosis in locations where complex laboratory equipment may not be accessible. Cellulose paper is an economical, compact and lightweight substrate for microfluidic devices, as passive capillary flow discards the need for an external pump due to its natural hydrophilicity [1]. Poly(vinylidene-co-trifluorethylene) (P(VDF-TrFE)) is a biocompatible and electroactive polymer characterized by its piezoelectricity: the ability to convert mechanical stimuli into an electrical response and vice-versa. This copolymer possesses high dielectric constant and excellent mechanical properties regardless of the processing method [2]. P(VDF-TrFE) can be tailored into oriented and non- oriented fibres membranes using electrospinning (ES) technique. It can also be tailored into porous films by using techniques based on phase inversion which allows porosity and pore size control: nonsolvent induced phase sepa- ration (NIPS), where the liquid or vapor phase in the polymeric solution is diffused by submerging it in a nonsolvent coagulation bath, and also by solvent evaporation (SE), where a fixed evaporation rate at room temperature results in controlled polymer crystallization [3]. P(VDF-TrFE) is hydrophobic, which prevents capillary flow through membranes or films. This can be overcome by using plasma treatment, which introduces functional groups into the surface of the material by exposure to plasma (Ar and O2 are commonly used) making it superhydrophilic [4]. Combined with wax-printing of hydrophobic barriers, a solutions can be guided to reaction chambers for analysis. Here we present a study on P(VDF-TrFE)-based electrospun membranes and porous films obtained by phase inver- sion as alternative substrates for the manufacture of μPAD devices. A comparison to the commonly used, commer- cially available Whatman No. 1 cellulose filter paper is also performed, along with wax-printing proofs of concept on the developed substrates. EXPERIMENTAL P(VDF-TrFE) with different morphologies were prepared by electrospinning - random and oriented fibres- , NIPS and SE – porous films. Plasma treatment (O2) was applied to all samples to tune their hydrophilicity and a specific design (carried out with a computer-aided design software) was printed on the substrates using a wax printer, and subsequently cured at 100 ºC to make the wax permeate the substrate and reach the opposite surface. A glucose assay kit (Trinder – Endpoint, FAR Diagnotics) was used on these substrates as proof of concept. RESULTS AND DISCUSSION