units, metal interconnects and input/output (I/O) pads distribute in this freestanding
network (Fig.5.1). We can load mesh electronics into a syringe and then inject
through a needle (Fig.5.6a) with mesh unfold to restore its original geometry
(Fig.5.6b, c). By precisely controlling the injection process, we can withdraw the
needle during injection to unfold mesh inside the targeted system and eject the I/O
region on the outside of the targeted system for the further electrical bonding and
connection to individually address electrical components delivered into the targeted
system.
In our design, the width of ribbons in the network is typically 5– 40 μm, the total
thickness is less than 800 nm and the size of unit cells is several hundred
micrometers. Figure5.7a shows a 3D reconstructed confocalfluorescence image of
a representative injection. 2-mm-wide mesh electronics was injected through a glass
needle with 95-μm inner diameters into PBS solution. This electronics has ribbons
with feature size of 5μm and thickness of 700–800 nm. We modify the mesh
electronics by poly-D-lysine (0.5–1.0 mg/mL, MW 70,000–150,000) to get a
hydrophilic surface to allow it to be suspended and unfolded in aqueous solution.
The stepwise process of a representative injection into a free solution is shown in
Fig.5.7b. Mesh electronics was loaded into a glass tube (with 95lm tip) as
described in experimental section. Glass needle was then detached from the syringe
and mounted onto a commercially available patch-clamp system. Microinjector is
connected to the glass needle to apply sufficient pressure (1 bar, 1–10 ms) for
injection.
Using microinjector, we can inject mesh electronics out gradually from needle
with injection rate at 5– 10 μm of mesh electronics per injection. we can control
Fig. 5.7 Stepwise injection.a3D reconstructedfluorescence image shows the electronics are
injected out from needle (blue dashed box) and subsequently self-unfolded in the solution.
bImages show that electronics are stepwise injected into solution by glass needle with diameter of
90 μm. Electronics was pushed to the tip of needle (I), electronics was partially injected out (II),
50% area of whole electronics was injected out, with partially unfolded mesh structure near needle
region (III) corresponding to the region highlighted by blue dashed box in (c), and completely
unfolded mesh structure (IV) corresponding to the region highlighted by white dashed box in (a)
5.3 Results and Discussion 79