Support-Material-Free Microfluidics on an Electrochemical Sensors Platform by Aerosol Jet Printing

Abstract

Printed electronics have led to new possibilities in the detection and quantification of a wide range of molecules important for medical, biotechnological, and environmental fields. The integration with microfluidics is often adopted to avoid hand-deposition of little volumes of reagents and samples on miniaturized electrodes that strongly depend on operator’s skills. Here we report design, fabrication and test of an easy-to-use electrochemical sensor platform with microfluidics entirely realized with Aerosol Jet Printing (AJP). We printed a six-electrochemical-sensors platform with AJP and we explored the possibility to aerosol jet print directly on it a microfluidic structure without any support material. Thus, the sacrificial material removal and/or the assembly with sensors steps are avoided. The repeatability observed when printing both conductive and ultraviolet (UV)-curable polymer inks can be supported from the values of relative standard deviation of maximum 5% for thickness and 9% for line width. We designed the whole microfluidic platform to make the sample deposition (20 μL) independent from the operator. To validate the platform, we quantified glucose at different concentrations using a standard enzyme-mediated procedure. Both mediator and enzyme were directly aerosol jet printed on working electrodes (WEs), thus the proposed platform is entirely fabricated by AJP and ready to use. The chronoamperometric tests show limit of detection (LOD) = 2.4 mM and sensitivity = 2.2 ± 0.08 µA/mM confirming the effectiveness of mediator and enzyme directly aerosol jet printed to provide sensing in a clinically relevant range (3–10 mM). The average relative standard inter-platform deviation is about 8%. AJP technique can be used for fabricating a ready-to-use microfluidic device that does not need further processing after fabrication, but is promptly available for electrochemical sample analysis.

Printed Smart Devices on Cellulose-Based Materials by means of Aerosol-Jet Printing and Photonic Curing

“…AJP is a full-additive, contactless printing manufacturing process composed of four key steps: Atomization of a liquid suspension by pneumatic or ultrasonic atomization thanks to a carrier gas (nitrogen or compressed dry air); generation of a mist of droplets (around 1-5 µm in diameter) passing through a virtual impactor to remove carrier gas and select droplets dimensions; focus of the stream by a sheath gas; deposition of the atomized ink on the substrate. This 3D printing technique was involved in the development of many applications, like high-efficiency solar and fuel cells, fully printed thin-film transistors, embedded resistors, antennas, MEMS, flexible displays and circuitry [33], photodetectors [34], wearable applications [35], thermistors [36], microelectrodes arrays for biosensing applications [37], lab-on-chip devices [38], protein [39] and glucose sensing [40].…”

Impedance-Based Monitoring of Mesenchymal Stromal Cell Three-Dimensional Proliferation Using Aerosol Jet Printed Sensors: A Tissue Engineering Application

“…Compared to those techniques, aerosol jet printing (AJP) allows an improvement both in terms of micrometer-resolution than in terms of the range of usable inks and substrates. Therefore, among the most recent technology used from this perspective, aerosol jet printing (AJP) indeed represents one of the most promising [30][31][32][33].…”

Aerosol-jet printing facilitates the rapid prototyping of microfluidic devices with versatile geometries and precise channel functionalization

“…The resolution of the printing technique allows features down to 10 μm laterally [ 24 ] and 0.5 μm vertically to be fabricated over a large area (15 × 15 cm 2 ) at a fraction of the cost, time and resources required by photolithography. Our technique differs from the recent work of Di Novo et al, who also used an AJP to make microfluidic devices by printing a material that can be UV cured instantly after leaving the tip [ 25 ]. Their method directly produces the channels and not a mold, and is prone to a deviation of 8% between prints [ 25 ].…”