Abdur Rub Abdur Rahman, Gusphyl Justin, Anthony Guiseppi-Elie
Center for Bioelectronics, Biosensors and Biochips (C3B)Department of Chemical and Biomolecular Engineering, and
Department of Bioengineering, College of Engineering and Science, Clemson University
Clemson, South Carolina [email protected] url=http://www.biochips.org
Electrochemical Characterization of
Implantable Biochips for Biosensing Application
Synopsis
MotivationpTrauma management in combat injury– glucose
and lactate sensingMethodologypUsing amperometry via Implantable
Electrochemical cell on a chip for biosensingFocuspDesign and characterize the working electrode
using Microdisc electrode Array (MDEA) architecture for enhanced mass transport and sensitivity.
Results penhanced sensitivities due to radial diffusion
Hyperglycemia is associated with excess mortality in critically ill patients [1].Early hyperglycemia (glucose >=200 mg/dL) is associated with significantly higher infection and mortality rates in trauma patients independent of injury characteristics [1].Decreased blood flow to the muscles -vasoconstrictionDecreased oxygen availability to the musclesIncreased oxygen debtIncreased lactic acid build up in the muscles
Lactate is a surrogate for oxygen debt
Importance of Glucose sensing to trauma
1 Laird, Amanda M., Miller, Preston, et al., Relationship of Early Hyperglycemia to Mortality in Trauma Patients, Journal of Trauma-Injury Infection & Critical Care. 56(5):1058-1062, May 2004.
Bonding pads
75 µm Au lines
Si3N4passivation
layer
Borosilicate glass
substrate
2000 µm
4000
µm
aa
d
Hexagonal closed
packed W.E.
a=100 µm, d=50 µm
Design of MDEA 5037 Electrochemical Cell chip
Radial vs. Semi-infinite Linear Diffusion
planarA planarmacroelectrodes
A vDCn10x 686.2i 21
21
apptox2
35p =
B
microboremicrodiscmicroelectrodes
πd8L8nFDCiss +
=
Si3N4
Au
Diffusion domain
Microdisc
2r
d
d
(a)
rd/2
Recessed depth = 0.5 µm
(b)
Diffusion profile of Microdisc Electrode Arrays
(a)
Glass Substrate
Au or Pt Metallization
(e)(e)
(c)(c)
(b)(b)
(a)
(d)(d)
(f)(f)
Glass Substrate
Au or Pt Metallization
Photosensitive ResistPhotosensitive Resist
Silicon Nitride PassivationSilicon Nitride Passivation
Fabrication of MDEAs
Fabricated MDEA 5037 and MDEA 050 electrodes
1 cm
2 cm
MDEA 050
b
Rs
CPE1
a
Determination of MDEA interfacial parameters by LPR and EIS
Interfacial and bulk parameters of Au, redox-free system
7.3 x 10-4
(0.0152)
7.3 x 10-4
(0.0152)
0.10 (0.1784)
cm2(cm)
Active area (radius)
17.9
18.4
15.0
ohm-cm
Resistivity
60321; 0.9142,465315037 lactate sensor
62919; 0.9141,095305037 glucose sensor
41.12700; 0.9140,0004,000MDEA 050
Rs (ohm)Q (nS.sn); n(nF/cm2)(nF)Working Electrodes
Interfacial parameters by EIS
Double layer capacitance by
LPR
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7-500
0
500
Pea
k C
urre
nt, I
p ( µ
A/c
m2 )
v1/2 (V1/2/s1/2)
Ip-anodicIp-cathodicSlope1Slope2R-S simulation
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7-500
0
500
Pea
k C
urre
nt, I
p ( µ
A/c
m2 )
v1/2 (V1/2/s1/2)
Ip-anodicIp-cathodicSlope1Slope2R-S simulation
Cyclic voltammetry in 1mM FcCOOH in 0.1M TRIS/0.1M KCL
0 200 400 600-400
-200
0
200
400
600
Voltage in mV
Cur
rent
in µ
A/c
m2 050
0 200 400 600-400
-200
0
200
400
600
Voltage in mV
Cur
rent
in µ
A/c
m2 5037
5037
050
5037
050
b
5037
050
c
a
EIS investigation of MDEA behavior
Integrated electronics for implantable wireless biosensor
RF Interface
Signal Conditioning ADC
MicroprocessorRAM FLASH
Transducer & Interface
Antenna
PowerModule
Common Electronics
Platform
RF Interface
Signal Conditioning ADC
MicroprocessorRAM FLASH
Transducer & Interface
Antenna
PowerModule
Common Electronics
Platform
RF Interface
Signal Conditioning ADC
MicroprocessorRAM FLASH
Transducer & Interface
Antenna
PowerModule RF Interface
Signal Conditioning ADC
MicroprocessorRAM FLASH
Transducer & Interface
Antenna
PowerModule
Common Electronics
Platform
Towards an on-chip dual potentiostat
Connector
Magnetic Field Sensor
Batteries
Antennae
PotentiostatAmplifiers
Data Converters
Processor
RF Transmitter
PSMBioChip System(Physiologic Status Monitoring)
4 cm
1.5 cm
Sensor Electronics
Transducer PC Board
PSM Microdisc die
Temperature Sensor(back of PC Board)
Medical-GradeRibbon Cable
An Implantable Biochip for Physiologic Status Monitoring
4 x 6 mm
4 x 1.5 x 0.5 cm
Discrete Prototype Device ASIC Device
Glucose, Lactate, pH and Temperature
PSMBioChip Wireless Monitoring
Implantable wireless telemetrySimultaneous glucose and lactate, temperature and possibly pH monitoring
Conclusion
MDEA WE containing ECC has been designed, fabricated and tested.
MEAD WE shows enhanced sensitivity due to radial diffusion profile.
on-chip sensing and telemetry electronics are being developed simultaneously for wireless implantability.
Acknowledgements
This work was supported by the US Department of Defense (DoDPRMRP) grant PR023081/DAMD17-03-1-0172 and by the Consortium of the Clemson University Center for Bioelectronics, Biosensors and Biochips. The authors acknowledge work to order contributions of Peter Hansen at Telesensors.
END