Low‐Power/High‐Gain Flexible Complementary Circuits Based on Printed Organic Electrochemical Transistors

Abstract

scaling law, states that the supply voltage for each new CMOS generation is reduced by 30%, and the power consumption subsequentially reduces by 50%. After decades of development, the latest 7-nm-node CMOS process reaches a supply voltage of 0.75 V. [2] Today, the Si-CMOS technology is heavily explored in Internet of Things (IoT) applications, serving as low-power outposts that record physical sensor parameters (e.g., motion, light, temperature), communicate over long distances, and harvest and store energy for its operation. [3] Expanding IoT modules with flexible, soft, or large-area chemical sensors and actuators only possible off-Si, enables a circuit technology that can amplify and route signals, facilitating signal compatibility and low-cost integration between Si-technology and embedded devices. Further, for many IoT and bioelectronic applications (e.g., (bio-)chemical sensors and neuronal interfacing), the on-site technology is preferably realized without Sichips to enable many different form factors, proximity, elasticity, and signal transduction, tailor-made for the actual chemical/biological environment. Also in this case, a low-power/voltage, high-performing, and flexible circuit technology operating at the site of stimulation or sensing is needed to record and transfer signals at high signal-to-noise performance. The ability to accurately extract low-amplitude voltage signals is crucial inseveral fields, ranging from single-use diagnostics and medical technology to robotics and the Internet of Things (IoT). The organic electrochemical transistor (OECT), which features large transconductance values at low operating voltages, is ideal for monitoring small signals. Here, low-power and high-gain flexible circuits based on printed complementary OECTs are reported. This work leverages the low threshold voltage of both p-type and n-type enhancement-mode OECTs to develop complementary voltage amplifiers that can sense voltages as low as 100 µV, with gains of 30.4 dB and at a power consumption of 0.1-2.7 µW (single-stage amplifier). At the optimal operating conditions, the voltage gain normalized to power consumption reaches 169 dB µW −1 , which is >50 times larger than state-of-the-art OECTbased amplifiers. In a monolithically integrated two-stage configuration, these complementary voltage amplifiers reach voltage gains of 193 V/V, which are among the highest for emerging complementary metal-oxide-semiconductorlike technologies operating at supply voltages below 1 V. These flexible complementary circuits based on printed OECTs define a new power-efficient platform for sensing and amplifying low-amplitude voltage signals in several emerging beyond-silicon applications.

Cyano‐Functionalized n‐Type Polymer with High Electron Mobility for High‐Performance Organic Electrochemical Transistors

“…[48] These performances, however, are still much inferior to their p-type counterparts, necessitating further investigation of high-performance n-type polymers and OECTs for applications such as biosensors [52][53][54] and low-power complementary circuits. [55][56][57] Based on the reported C* and μ values for n-type OECTs (Table S1, Supporting Information), it is quite clear that the electron mobility μ is the limiting factor in obtaining high μC*. For n-type polymers, via hydrophilic side-chain and/ or backbone structure engineering, high C* of several hundred F cm −3 can be achieved which is on par with the p-type polymers.…”

Organic electrochemical neurons and synapses with ion mediated spiking

“…A c-OECT inverter, comprising a pair of P(g 4 2T-T) and BBL OECTs, is made to build the amplifying block in the A-H circuit (Supplementary Figure 2 ). The maximum DC voltage gain of the inverter is 26 (V/V) and we can reach nearly 200 (V/V) by cascading two inverters to form the amplifying block 34 . The fully printed OECN is shown in Fig.…”

“…The P(g 4 2T-T) and BBL nanoparticles are respectively collected by centrifugation (5000 rpm, 30 min) and washed in IPA six times until neutral. The neutral P(g 4 2T-T) and BBL nanoparticles are re-dispersed in IPA to obtain dispersion inks (about 0.006 mg/mL for P(g 4 2T-T) and 0.1 mg/mL for BBL) 34 , 46 .…”

“…Ag/AgCl ink is blade coated through a shadow mask and annealed at 120 ο C for 10 min to form the gate. The P(g42T-T) and BBL layers are deposited by spray-casting in air through a shadow mask, using a standard HD-130 air-brush (0.3 mm) at an atomization air pressure of 1 bar 34 .…”

Sub-3V, MHz-Class Electrolyte-Gated Transistors and Inverters

“…In our view there are clear reasons why EGTs will not rival the speed of Si MOSFETs 2 (though perhaps not everyone agrees 38 ), but for envisioned applications of EGTs, gigahertz speeds do not appear necessary. As EGTs are being developed as physiological recording amplifiers 9,10 , and integrated into circuits 36,[39][40][41] and neural nets 4,11,13,14,16 , it is nevertheless important to establish the limits of performance that can be obtained by rational design. We note that there are other limitations to EGT performance like high dielectric loss tangents and quasi-static leak currents associated with electrolytes that are important for power consumption 2 , but these are not our focus here.…”