Lebenslauf - Life Science Nord

Design of a Wearable, Wireless Balance System for Patients with
Peripheral Neuropathy (P)
Thomas Weber, Fakultät Life Sciences, Studiendepartment Medizintechnik,
Hochschule für Angewandte Wissenschaften Hamburg,
Lohbrügger Kirchstrasse 65, 21033 Hamburg,
Thomas.Weber@rzbd.HAW-Hamburg.de; Tel. 040-18055674
Aim
Neurological diseases affect integrative motor function, such as the control of balance, as well as
the sensation of pain. A common form of neurological disease is peripheral neuropathy. Several
studies have shown that loss of plantar sensation, caused by peripheral neuropathy, leads to a decreased
balance regulation and a higher risk of falls. The aim of this project was to develop a bionic
system to substitute the plantar pressure receptors and provide feedback information to the patient
through vibrations generated by tactors in a cuff worn around the legs or arms. The system substitutes
lost foot sole pressure information and helps improve stability during gait and stance. The
entire system fits into the heel of a shoe with sensors distributed across the sole.
Methods
The substitution system consists of three subsystems: the sensory system, the processing system,
and the transmitting system. The current project was focused on the design of the In-Shoe sensory
system termed BluePic. Capacitive pressure sensors that were fairly linear and nearly unaffected
by temperature shifting were custom built for the application using a sandwiching technique. The
capacitive value of the pressure sensor is collected by Capacitive-to-Digital Converters. The Microcontroller
calculates the Center of Pressure and chooses the tactors to vibrate. The tactor addressing
is transmitted wireless over the Bluetooth device to the cuff. The board has an outline of 38mm
x 32mm and about 80 parts are placed on it, including a charging circuit for the battery and a connector
for the sensors. The Microcontroller is programmed in C. The software controls the capacitive
converters, the Bluetooth device, and the periphery. A LabView-based program is used to display
the collected pressure values from the sensor output as well as the pressure distribution.
Results
The BluePic device collects pressure values of seven sensors placed at the areas of the highest
pressure occurrence in the shoe sole during gait and stance. The Microcontroller calculates the
Center of Pressure and interprets it in dependence to the patient’s Center of Mass and status of
balance distribution. The system uses this information to decide which tactors to activate to provide
a feedback signal to the wearer. This tactor addressing is transmitted wirelessly to the cuff.
Conclusion
Patients may now substitute their lost plantar sensation by wearing a simple sensory system. The
system can help to maintain balance during gait and stance. The response to the system is initially
conscious but it is possible that patients may respond subconsciously after an extended period of
training.
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