Peer review of: Multiscale real time and high sensitivity ion detection with complementary organic electrochemic (2020)

Reviewers' Comments: 
Reviewer #1: 
Remarks to the Author: 
Comments 


The paper written by Paolo Rmele et al. describes complementary organic electrochemical 
transistors amplifier by connecting p-type and n-type OECT for real time detection of ion 
concentration. The authors showed somehow acceptable sensing performance depending on the 
concentration of ion, however it is difficult for the reviewer to find novelty and ground-breaking 
compared to the other researches. Thus, the reviewer suggests that this manuscript is not suitable 
for the publication and recommends submission of this article to more specialized journals. Here 
are some comments for this paper. 
 
1) This article introduces the complementary organic electrochemical transistors amplifier for 
multiscale real time ion detection. However, there are many researches about ion-sensitive organic 
electronics as mentioned in main context. The reviewer feels that the authors should consider 
practical and feasible demo- and application in biomedical field for novelty of this research. 
2) In this article, selective ion detection based on the complementary OECTs amplifier in Figure 6 
with potassium (K+) and sodium ion (Na+) which are components of physiological system. The 
selectivity of the amplifier is described so well by real time monitoring, however, there are other 
ions in physiological system such as calcium ion (Ca2+) having higher charge compared to ions 
mentioned above. So, the reviewer feels that the authors should add experimental results from 
other ions having the charge more than +1 for better demonstration. 
3) The authors show higher sensitivity of the complementary OECTs amplifier in Figure 4 than that 
of a single OECT with PEDOT:PSS. However, there is no obvious explanation about the relationship 
between concentration of ions and sensitivity that the higher concentration results in the larger 
value of sensitivity in Figure 4c. The authors should supply more detail about it. 
4) The authors successfully construct the complementary OECTs amplifier with each p-type and n-
type OECT. Especially, p-type OECT is operated by depletion mode from compensation of the effect 
of anionic sulfonate groups on the PSS. However, complementary logic circuits with both p- and n-
type OECT by accumulation mode (Adv. Mater. 2018, 30, 1704916). It would be better if there are 
specific reasons that why the authors utilized the depletion mode OECT in this paper. 
 
 
 
Reviewer #2: 
Remarks to the Author: 
The paper regards the realization of an OECT transistor amplifiers, based on two OECT transistor 
one p type based on PEDOT:PSS and one n type based on BBL. The sensing of ions in solution is a 
well-known application for these devices, but the realization of an amplifier, is an interesting 
development, because it allows to explore the potential advantage of these devices. In particular, 
the authors show a high sensitivity of the complementary amplifiers, that overcome the 
fundamental limit. These results are original and shows all the potential of OECT, as part of a logic 
system, with their characteristics of large transconductance. The paper is well written and clear. 
The case of an ion selective membrane is also showed to enhance the selectivity of the device. The 
data are convincing and I suggest to publish the paper, because it could be a reference for the 
sensitivity of these devices. Maybe an actual image of the device in the supporting is useful. 
 
 
 
Reviewer #3: 
None