Page 445 - Handbook of Biomechatronics

The Artificial Pancreas 439

alarm indicating a fault condition. Even the beeper is provided with a self-
test capability based either on its impedance or feedback through a separate
microphone. Some pumps also incorporate eccentric rotating mass vibrators
to provide an additional warning capability.
All pumps must be ESD protected. This can be built into the electronics
or provided across any exposed lines using separate electronics
(Mossman, 2010).

4.2.6 Data Exchange
Data ports (typically USB) are included on most pumps to allow logged data
to be transferred to a PC and to download firmware upgrades. In addition,
RF interfaces are common in modern pumps, allowing them to be linked to
continuous glucose monitors for closed-loop control. Wireless interfaces are
generally implemented using Bluetooth or other ISM band links (Mossman,
2010; Ganesan, 2013).

4.3 Implantable Insulin Pumps
Given the requirements for continuous insulin provision, a totally implant-
able insulin pump would appear to be the ideal way to minimize regular
cannulization and potential infection resulting from the use of external
pumps. The process started in 1970 with a paper describing a multipurpose
permanently implantable infusion pump that could be used for heparin or
insulin delivery (Blackshear et al., 1970). This was followed by a paper that
described an ingenious method to use the vapor pressure of an isolated fluid
as an energy source to deliver the drug at a single constant rate as shown in
Figs. 19 and 20 (Blackshear et al., 1972).
For a liquid infusate with viscosity, η (pa.s), and a pressure differential
3
along the capillary is ΔP (Pa), the volume flow rate Q (m /s) described
by Poiseuille’s law is
dV ΔPπR 4
Q ¼ ¼ (5)
dt 8ηL

where R (m) is the radius of the cannula and L (m) is its length.
Later revisions of the pump used a magnet to alter the settings of an inter-
nal valve that could change the flow rate by actuating a valve to lengthen or
shorten the capillary length and hence change the flow rate according to the
Poiseuille relationship.
Human trials of intravenous (IV) infusion of insulin started in 1980 using
the Infusaid Model 400, Constant Rate infusion pump (Buchwald et al., 1981).