We used a commercial screen-printed three-electrode cell (DRP-110CNT-GNP,
DropSens, Llanera, Spain) for performing CA, SWV, and CV on 10 μM–10
mM ferricyanide. We tested the potentiometric mode of UWED using in-house-built
K+ and Na+ ion-selective electrodes (ISEs),
which we fabricated according to protocols established in the literature.39Supporting Information lists the details of solution preparation and electrochemical measurements.
The fabrication of the UWED occurred as follows: Using the free
version of CAD software Eagle (version 7.6), we designed the UWED
in two steps: (i) we first designed the circuit diagram (Figure S1 ), and (ii) we then designed the route
of the wires and layout of the components on a two-layer printed circuit
board (PCB).Figure S2 shows the design
and layout of the PCB. We verified the design of the PCB using design
rule check and then fabricated it using a commercial custom PCB service
(Silver Circuits Sdn. Bhd., Selangor, Malaysia). We ordered all other
circuit components from Digi-Key Electronics (Thief River Falls, MN);Table S3 lists the details of the circuit components.
We surface-mounted the components on the PCB and manually soldered
them to the PCB. To ensure the board does not have any false connections,
we inspected it under a microscope and tested the connections with
a multimeter.
We wrote the firmware of the microcontroller (RFduino)
in the Arduino
software v1.6.5 with the RFduino board package v2.3.1. To load the
firmware onto the microcontroller, we attached temporary wires to
the contact pads on the PCB, and connected the other end to the terminals
of a USB shield for RFduino (RFD22121). We removed the temporary wires
after loading the firmware. We then soldered the socket to connect
to the commercial ceramic card with screen-printed electrode, and
the Li-polymer battery (LiPo) to the contact pads. We designed the
housing for the UWED in AutoCAD 2013, exported the file as an STL
file, and 3D-printed the case in acrylonitrile butadiene styrene (ABS)
using a 3D printer (StrataSys Fortus 250mc).Figure S3 shows the housing and components of UWED before assembly.
After assembly, we charged the internal battery with an external LiPo
charger (connected to the charging port of UWED). We developed the
software for the smartphone and tablet in techBASIC 3.3.3 (Byte Works
Inc.) and tested the software on an iPhone 6S and iPad Mini (Apple).
The software saves the data in the text format and sends it to the
Cloud (for storage and further processing) over e-mail protocol. We
analyzed the results of the electrochemical measurements in MatLAB
R2014b.
DropSens, Llanera, Spain) for performing CA, SWV, and CV on 10 μM–10
mM ferricyanide. We tested the potentiometric mode of UWED using in-house-built
K+ and Na+ ion-selective electrodes (ISEs),
which we fabricated according to protocols established in the literature.39
The fabrication of the UWED occurred as follows: Using the free
version of CAD software Eagle (version 7.6), we designed the UWED
in two steps: (i) we first designed the circuit diagram (
of the wires and layout of the components on a two-layer printed circuit
board (PCB).
and layout of the PCB. We verified the design of the PCB using design
rule check and then fabricated it using a commercial custom PCB service
(Silver Circuits Sdn. Bhd., Selangor, Malaysia). We ordered all other
circuit components from Digi-Key Electronics (Thief River Falls, MN);
We surface-mounted the components on the PCB and manually soldered
them to the PCB. To ensure the board does not have any false connections,
we inspected it under a microscope and tested the connections with
a multimeter.
We wrote the firmware of the microcontroller (RFduino)
in the Arduino
software v1.6.5 with the RFduino board package v2.3.1. To load the
firmware onto the microcontroller, we attached temporary wires to
the contact pads on the PCB, and connected the other end to the terminals
of a USB shield for RFduino (RFD22121). We removed the temporary wires
after loading the firmware. We then soldered the socket to connect
to the commercial ceramic card with screen-printed electrode, and
the Li-polymer battery (LiPo) to the contact pads. We designed the
housing for the UWED in AutoCAD 2013, exported the file as an STL
file, and 3D-printed the case in acrylonitrile butadiene styrene (ABS)
using a 3D printer (StrataSys Fortus 250mc).
After assembly, we charged the internal battery with an external LiPo
charger (connected to the charging port of UWED). We developed the
software for the smartphone and tablet in techBASIC 3.3.3 (Byte Works
Inc.) and tested the software on an iPhone 6S and iPad Mini (Apple).
The software saves the data in the text format and sends it to the
Cloud (for storage and further processing) over e-mail protocol. We
analyzed the results of the electrochemical measurements in MatLAB
R2014b.
