SUPPLEMENTAL MATERIAL
A hydrogel capsule as gate dielectric in flexible organic field-effect transistors
L. M. Dumitru,1 K. Manoli ,1 M. Magliulo,1 T. Ligonzo,2 G. Palazzo,1,3 and
L. Torsi1,a)
Department of Chemistry, “Aldo Moro “University, Bari, Via Orabona 4, I-70126, Italy
1
Department of Physics, “Aldo Moro “University, Bari, Via Orabona 4, I-70126, Italy
2
Center of Colloid and Surface Science – CSGI – Bari Unit, Via Orabona 4, I-70126, Italy
3
No.
Contents
Page
1.
Output characteristic of a water-gated OFET
S1
2.
Table showing a comparison between the electrical performances of a
water-gated and an alginic acid capsule-gated OFET
S2
3.
Graphical comparison for output characteristics of a dry alginic acid
membrane-based OFET (fully soaked and fully cross-linked) and alginic acid capsule-based OFET
S2
4.
Sodium alginate/water acid base equilibrium
S2
5.
Sqrt. of polyalginate concentration versus IDS current graph
S3
6.
GOx/HRP – glucose colorimetric assay
S3
Figure S1. Output characteristics of a water-gated pBTTT-C14 based OFET
S1
a)
AA capsule gated OFET
µ (cm2 V-1 s-1)
Average
(n=3)a)
(1.4 x 10-2 ± 1.5 x 10-3)
1.5 x 10-2
VT (V)
(-0.05 ± 0.01)
-0.004
on/off
(311 ± 170)
438
Water gated
OFET
µ (cm2 V-1 s-1)
(2.6 ± 1.2) x 10-2
3.3 x 10-2
VT (V)
(0.19 ± 0.14)
0.03
on/off
(16 ± 11)
29
Best
the values are expressed as the average over 3 replicates and errors are the relevant standard deviation
Table S1. Comparison between electrical performances of water-gated and
AA capsule-gated OFET
Figure S2. Output Characteristics of a dry AA membrane a) fully soaked AA membrane) and fully cross-linked AA
capsule c)
Sodium alginate/water acid base equilibrium
Let us assume those hydroxyl groups (OH-) efficiently dope the OS thus decreasing the measured on current. When on ads
poly-alginate sodium salt (pANa) to the water the following acid-base equilibrium takes place:
𝑝𝐴 ∙ 𝑁𝑎 + 𝐻2 𝑂 ⇌ 𝑝𝐴− + 𝑁𝑎 + + 𝐻2 𝑂 ⇌ 𝑁𝑎 + + 𝑝𝐴𝐻 + 𝑂𝐻 −
With a constant of basic dissociation
S2
𝐾𝑏 =
[𝑝𝐴𝐻][𝑝𝐴𝑂𝐻 − ]
[𝑂𝐻 − ]2
[𝑂𝐻 − ]2
=
≈
−
−
[𝑝𝐴 ]
[𝑝𝐴 ∙ 𝑁𝑎]𝑡𝑜𝑡 − [𝑂𝐻 ] [𝑝𝐴 ∙ 𝑁𝑎]𝑡𝑜𝑡
the OH- concentration, thus the extent of doping (i.e. the decrease in current), should be proportional to the square-root of
the polyalginate concentration. Indeed this is observed over three orders of magnitude in concentration
-1.0
-1.5
IDS /A
-2.0
-2.5
-3.0
-3.5
-4.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
[pA] (wt%)
Figure S3. IDS current increases with the sqrt of the polyalginate concentration.
GOx/HRP enzymatic reaction
The glucose oxidase (GOx) in the presence of β-D-glucose catalyses the following reaction:
β-D-glucose + GOx → D-gluconolactone + GOx-H2
GOx-H2 + O2 → GOx + H2O2
The colorimetric indicator acts on the hydrogen peroxide produced that, scavenged by the horseradish peroxidase (HRP),
is reduced by an electron donor 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) dye that turns its colour into
blue-green:
H2O2 + Dye-red → Dye-ox + H2O
S3