Toward Complementary Ionic Circuits: The npn Ion Bipolar Junction Transistor

Abstract

Many biomolecules are charged and may therefore be transported with ionic currents. As a step toward addressable ionic delivery circuits, we report on the development of a npn ion bipolar junction transistor (npn-IBJT) as an active control element of anionic currents in general, and specifically, demonstrate actively modulated delivery of the neurotransmitter glutamic acid. The functional materials of this transistor are ion exchange layers and conjugated polymers. The npn-IBJT shows stable transistor characteristics over extensive time of operation and ion current switch times below 10 s. Our results promise complementary chemical circuits similar to the electronic equivalence, which has proven invaluable in conventional electronic applications.

Logic gates based on ion transistors

“…1). Two types of transistors can then be constructed, the npnIBJT 14 (Fig. 1a) that conducts anions from the emitter to the collector, and the pnpIBJT 4 (Fig.…”

“…Nanofluidic bipolar transistors have been proposed 12 and fixed pnpjunctions was implemented in a polymer pore 13 ; however, both of these devices still operates in the fieldeffect mode compared with BJTs in which the conduction occurs throughout the bulk of the conductor. To overcome the limitations of surface charge modula tion, we have previously developed another type of ion transistor, the ion bipolar junction transistor 4,14 (IBJT), which is based on thin layers of ion selective membranes 15 and conductive polymers 16,17 . IBJTs shows overall good transistor characteristics, in terms of, for instance, a high ion current on-off and gain, and have success fully been utilized to modulate the delivery of neurotransmitter to regulate signalling of neuronal cells 4 .…”

Polyphosphonium-based bipolar membranes for rectification of ionic currents

“…The effect can be suppressed by incorporating a neutral electrolyte inside the BM, 10,18 for instance, poly(ethylene glycol) (PEG). 2,6,7 However, as previously reported, 2 the PEG volume will introduce hysteresis when switching from forward to reverse bias, due to its ability to store large amounts of charges. This was circumvented by ensuring that only H þ and OH À are present in the diode, which recombines into water within the PEG volume.…”

“…One approach to achieve a chemical circuit technology is to use bipolar membranes (BMs), which can be used to create the ionic equivalents of diodes 2-5 and transistors. [6][7][8] A BM consists of a stack of a cation-and an anionselective membrane, and functions similar to the semiconductor PN-junction, i.e., it offers ionic current rectification 9,10 (Figure 1(a)). The high fixed charge concentration in a BM configuration make them more suited in bioelectronic applications as compared to other non-linear ionic devices, such as diodes constructed from surface charged nanopores 11 or nanochannels, 12 as the latter devices typically suffers from reduced performance at elevated electrolyte concentration (i.e., at physiological conditions) due to reduced Debye screening length.…”

“…In this work, we present a non-amine based BM diode that avoids EFE water dissociation, enables easy miniaturization, and provides fast turn-off speeds and high rectification. An anion-selective phosphonium-based polycation (poly(vinylbenzyl chloride) (PVBC) quaternized by triphenylphospine, PVBPPh 3 ) was synthesized and compared to the ammonium-based polycation (PVBC quaternized by dimethylbenzylamine, qPVBC) previously used in BM diodes 2 and transistors, 7,8 when included in BM diode structures together with polystyrenesulfonate (PSS) as the cation-selective material (Figure 1(b)). Three types of BM diodes were fabricated using standard photolithography patterning (Figure 1(c)), either with qPVBC (BM1A and BM2A) or PVBPPh 3 (BM1P) as polycation and either with (BM2A) or without PEG (BM1A and BM1P).…”