3-D printed adjustable microelectrode arrays for electrochemical sensing and biosensing

Abstract

Printed Electronics has emerged as an important fabrication technique that overcomes several shortcomings of conventional lithography and provides custom rapid prototyping for various sensor applications. In this work, silver microelectrode arrays (MEA) with three different electrode spacing were fabricated using 3-D printing by the aerosol jet technology. The microelectrodes were printed at a length scale of about 15 μm, with the space between the electrodes accurately controlled to about 2 times (30 μm, MEA30), 6.6 times (100 μm, MEA100) and 12 times (180 μm, MEA180) the trace width, respectively. Hydrogen peroxide and glucose were chosen as model analytes to demonstrate the performance of the MEA for sensor applications. The electrodes are shown to reduce hydrogen peroxide with a reduction current proportional to the concentration of hydrogen peroxide for certain concentration ranges. Further, the sensitivity of the current for the three electrode configurations was shown to decrease with an increase in the microelectrode spacing (sensitivity of MEA30: MEA100: MEA180 was in the ratio of 3.7: 2.8: 1), demonstrating optimal MEA geometry for such applications. The noise of the different electrode configurations is also characterized and shows a dramatic reduction from MEA30 to MEA100 and MEA180 electrodes. Further, it is shown that the response current is proportional to MEA100 and MEA180 electrode areas, but not for the area of MEA30 electrode (the current density of MEA30 : MEA100 : MEA180 is 0.25 : 1 : 1), indicating that the MEA30 electrodes suffer from diffusion overlap from neighboring electrodes. The work thus establishes the lower limit of microelectrode spacing for our geometry. The lowest detection limit of the MEAs was calculated (with S/N = 3) to be 0.45 μM. Glucose oxidase was immobilized on MEA100 microelectrodes to demonstrate a glucose biosensor application. The sensitivity of glucose biosensor was 1.73 μAmM-1 and the calculated value of detection limit (S/N = 3) was 1.7 μM. The electrochemical response characteristics of the MEAs were in agreement with the predictions of existing models. The current work opens up the possibility of additive manufacturing as a fabrication technique for low cost custom-shaped MEA structures that can be used as electrochemical platforms for a wide range of sensor applications.

Electrochemical biosensors for pathogen detection

“…The aforementioned emerging manufacturing processes are also used to construct electrode arrays that exhibit geometries other than interdigitated designs for electrochemical sensing applications. For example, Yang et al used aerosol jet additive manufacturing to fabricate silver (Ag) microelectrode arrays (Yang et al 2016a).…”

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].…”

Optimization of makerspace microfabrication techniques and materials for the realization of planar, 3D printed microelectrode arrays in under four days

“…1 Another benet of glass is that it is an insulator, so any conduction is mainly in the traces leading to a less noisy signal with better Signal-to-Noise Ratio (SNR). Since MEA are used with living cells in culture for several weeks and in some assays months, the biocompatible properties 10,11 of glass additionally make it a good substrate material to fabricate MEAs. The process of fabricating glass MEAs typically involves microfabrication in a cleanroom environment, which involves long fabrication timelines.…”