Science - USA (2022-05-27)

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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