Choiet al., Science 376 , 1006–1012 (2022) 27 May 2022 3of7
0200400
10
20
30
40
0 100 200 300 400
100
150
200
250
50 100 150
90
95
100
0 500n 1μ
-4
0
4
8
0 102030405060
0
20
40
60
80
100
120
510152025
-1.5
-1.0
-0.5
0.0
B^
Frequency (MHz)
S11 (dB)
G Cardiac module
ECG AFE
MCU
Bluetooth
PMIC
Wireless
charging
Li-pol
battery
RF power
transistor
X-tal
Tx and Rx
antenna
Charging
coil
Powering
coil
Matching
circuit
On
/Off
Control module
H
A
F
0 5 10 20 25 30
0
5
10
15
20
Time (days)
Output voltage (V
oc
)
Ref- module (W/Mg)
Biores- module (Mo)
Time (days)
Mass released (%)
E
0180360
Angle (°)
01530
5
10
15
20
Strain (%)
dcoil(mm)
( egatlov tuptu
OV
oc
)
D
25
18
12
50:50
75:25
65:35
0246810
0
2
4
6
Time (s)
ECG (A.U.)
I
Cardiac module
Gold standard
b-DCPU
encapsulation
Stretchable
electrode
Rx coil
Si NM
diode
Power
harvester
Stimulation
electrode
Stretchable
interconnect
Wax
paste
Steroid-
eluting
patch
C
Time (s)
Voltage (V)
Input (transmitting)
Output
dcoil(mm)
12
18
25
Silicone elastomer
Cu traces Li-polymer battery
Polyimide
Components
Epoxy stiffener
Silicone elastomer
Coil
(charging)
Coil
(powering)
(BLE, ECG,
memory, PMIC,
wireless charging)
Time (s)
Heart rate (bpm)
J
Cardiac module
Gold standard
Time (s)
Respiratory rate (rpm)
K
Resp- module
Gold standard
Time (s)
SpO
2
(%)
L
Hemo- module
Gold standard
Hold breath
(glycolic acid
:lactic acid)
Fig. 2. Materials, design features.(A) Schematic illustration of a bioresorbable
module. (B)S 11 values of the Rx coils with different diameters (dcoil). ( C) Example
output waveform (red;dcoil= 12 mm) wirelessly generated by an alternating
current (black; ~6Vpp; 13.56 MHz) applied to the Tx coil. (D) Output open
circuit voltage (VOC) of devices as a function of tensile strain (left) and twist angle
(right) at a fixed transmitting voltage (8Vpp) and frequency (13.56 MHz).
(E) Drug-release behaviors of steroid-eluting patches with three different
ratios of base polymer. Error bars represent standard deviation.
(F) Measurements ofVOCof the bioresorbable module (red squares; 10-mm-
thick Mo) and a reference module (black circles; 700-nm-thick W coated
50-μm-thick Mg) immersed in PBS (37°C). (G) Schematic illustration of a
skin-interfaced cardiac module. PMIC, power management integrated circuit.
(H) System block diagram of the cardiac module. (I to L) Comparisons of ECG, HR,
respiratory rate, and SpO 2 levels determined by the skin-interfaced modules [red;
cardiac module in (I) and (J); respiratory module in (K); hemodynamic module in
(L)] and a reference device (black). In (L), data were collected from a healthy subject
who held their breath for 60 s (yellow background). A.U., arbitrary units; rpm,
respirations per minute.
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