Liquid–Solid Dual-Gate Organic Transistors with Tunable Threshold Voltage for Cell Sensing

Abstract

Liquid electrolyte-gated organic field effect transistors and organic electrochemical transistors have recently emerged as powerful technology platforms for sensing and simulation of living cells and organisms. For such applications, the transistors are operated at a gate voltage around or below 0.3 V because prolonged application of a higher voltage bias can lead to membrane rupturing and cell death. This constraint often prevents the operation of the transistors at their maximum transconductance or most sensitive regime. Here, we exploit a solid-liquid dual-gate organic transistor structure, where the threshold voltage of the liquid-gated conduction channel is controlled by an additional gate that is separated from the channel by a metal-oxide gate dielectric. With this design, the threshold voltage of the "sensing channel" can be linearly tuned in a voltage window exceeding 0.4 V. We have demonstrated that the dual-gate structure enables a much better sensor response to the detachment of human mesenchymal stem cells. In general, the capability of tuning the optimal sensing bias will not only improve the device performance but also broaden the material selection for cell-based organic bioelectronics.

Real-Time Monitoring of Cellular Cultures with Electrolyte-Gated Carbon Nanotube Transistors

“…The excellent works by Róisín Owens and collaborators have in part overcome the limitations of standard ECIS, demonstrating organic electrochemical transistors able to detect and measure cell adhesion, proliferation and detachment in vitro with enhanced sensitivity and temporal resolution compared to standard technologies, with the added advantage of allowing for simultaneous electrical and optical analyses. 8,9 Nonetheless, the electric approaches so far reported for cell viability monitoring, whether performed with electrodes or with transistors, are still based on step-function response analysis or AC measurements, either frequency-dependent or single-frequency, with the only exception of tubular transistors for 3D cell cultures monitoring, recently proposed by Pitsalidis et al [8][9][10][11][12] The rather complex instrumentation required for this type of measurements, along with the need for reliable and well-established equivalent electrical models of the cell-substrate impedance for data interpretation, do not favor the large-scale automation and parallelization of these techniques, along with their portability. In this work we demonstrate that a low-voltage electrolyte-gated field-effect transistors (EGFETs), based on a solution-processed network of single-walled carbon-nanotubes (SWCNT), is able to provide information on the adhesion, proliferation and detachment processes in three different cell models, through the modification of the drain-source quasi-static current of the device, without need for electrical impedance measurements and related modeling.…”

Organic semiconductors for biological sensing

“…The dual-gated device displayed a threefold sensitivity and a faster response time than its singlegated analogue, and demonstrated high operational stability above a bottom-gate voltage of -3 V, which the authors attributed specifically to the use of DPP-DTT, citing its uniform, ordered morphology as observed by AFM and grazing incidence wide-angle X-ray scattering (GIWAXS). 153 Since then, the biocompatibility of polymers of this type has been improved further. Citing the facile covalent functionalization of the DPP moiety as the reason for its suitability for this purpose, in 2018 Du et al exchanged the C8/C10 side chain of a similar polymer, diketopyrrolopyrroleterthiophene (DPP3T), for poly-L-lysine.…”

Transistors for Chemical Monitoring of Living Cells

“…Liquid electrolyte-gated organic field effect transistors for cell monitoring are reviewed in the next section, but the work of Zhang et al [ 88 ] can be considered in this section, because the architecture of their device was based on a dual gate (i.e., in-between the classical bottom-gated OFET and the EGOFET). In this work, the bottom gate was used in order to shift the operating domain within the range where the transconductance reaches its maximum ( Figure 18 ).…”

“… ( a ) Architecture of the dual-gate transistor, with a Ag/AgCl top gate and cells attached to the DPP-DTT semiconductor (poly[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno[3,2-b]thiophene)]; ( b ) time-dependent drain current curves showing cells detachment upon addition of trypsin. Reprinted with permission from Zhang et al [ 88 ]. Copyright © 2017 American Chemical Society.…”