Thai-Australian Biomedical Engineering

Collaboration in Development of a Blood Collection Monitor

Chanchai Thaijiam Department of Electrical Engineering

Srinakharinwirot University Nakhonnayok Province, Thailand

chanchait@swu.ac.th

Abstract-A case study is presented involving the early stage of

a collaborative Biomedical Engineering project between Thai and

Australian researchers. The case study involves development of a

blood collection monitor intended potentially to fill the needs of

Thai hospitals. Results of developing this medical device were

found from particular experiments.

Index Terms-Blood Collection Monitor, Medical Devices,

Collaborative Biomedical Engineering, Thailand-Australia

Research Collaboration.

I. INTRODUCTION

Here we first briefly discuss Biomedical Engineering collaboration between Thailand and Australia and then present a case study.

Thailand and Australia have long had academic Engineering links, including examples such as Thai Engineering students entering Australian universities nearly 60 years ago under the Colombo Plan. These

.Iinks have be�n

highly valued by both countries, both academIcally and also m terms of interchange of culture and friendship [1]. A particular example of this are the links developed between the School of Engineering CUT AS Engineering) at the University of Tasmania in Australia and Thai universities. UT AS Engineering's early contact with Thailand includes Thai students studying Engineering in Tasmania under the Colombo plan in the 1970's, which resulted in development of strong and friendly personal relationships between Engineers of both countries. UTAS Engineering again became involved in the 1990's with a Civil Engineering twinning program with King Mongkut's University of Technology Thonburi (KI�;JlJT:f). This was followed ten years ago by UT AS Engmeermg teaching an Advanced Diploma of Engineering at Srinakharinwirot University (SWU), and a number of SWU staff subsequently coming to UT AS Engineering to complete Engineering research higher degrees, including author Dr. Chanchai Thaijiam, who's thesis involved a Biomedical Engineering topic [2,3]. Two years ago the Australian

Le Minh Diep Khong, Timothy John Gale* School of Engineering

University of Tasmania Hobart, Australia

T.Gale@utas.edu.au*

Endeavour Awards program further encouraged UT AS Engineering and Thai links by supporting an extended visit to Thailand by author Dr. Timothy Gale, with the main purpose of the visit being to encourage Biomedical Engineering collaboration between Australia and Thailand. One outcome of this is that UTAS Engineering and SWU are currently exploring the potential for collaboration and clinical engagement [4] through Biomedical Engineering projects. A proposed project resulting from this is described in this paper in the form of a case study.

Before introducing the case study, it is interesting to note the potential for academic collaboration between the Australian and Thai universities that conduct teaching and research programs in Biomedical Engineering. At least fifteen universities are active in Biomedical Engineering in Australia, including Flinders University, Griffith University, Latrobe University, Monash University, Murdoch University, Queensland University of Technology, RMlT, Swinburne University of Technology, University of Melbourne, University of New South Wales, University of Queensland, University of South Australia, University of Sydney, University of Tasmania, and University of Technology, Sydney. Thai universities are active in Biomedical Engineering, including Mahidol University, Chulalongkom University, King Mongkut's Institute of Technology Ladkrabang (KMTTL), Srinakharinwirot University (SWU), Chiang Mai University, Rangsit University, Prince of Songkla University, and King Mongkut's University of Technol�gy North Bangkok (KMUTNB). Given the much larger populatIOn in Thailand than in Australia, there appears to be potential for growth in Thai Biomedical Engineering academic training, and it seems likely that there may be significant growth in the number of Thai universities active in Biomedical Engineering in the future.

A related aspect is also the potential for growth and academic engagement with the Biomedical Engineering industry, such as the Medical Device industry. This ind�stry currently has many participants, and there are some relatIvely

large ones that stand out such as Cochlear and RESMED in Australia. However, when viewed in comparison to the USA as the global leader in this area, we see there is also substantial scope for development of the Biomedical Engineering industry in both Australia and Thailand and of academic programs and research playing an important part in this.

The proposed Biomedical Engineering project will now be described as a case study. The proposed project is a potentially industry-relevant project involving development of a "Thai" Blood Collection Monitor (BCM). A BCM is helpful for accurate blood collection and also provides a smooth rocking frequency, mixing blood with anticoagulants in a blood collection bag. BCMs are used in the collection of blood from blood donors and are a commonly used medical device around the world and also in Thai hospitals. A collection needle inserted into the vein of a donor draws blood from the patient through a cannula and into a blood collection bag that is located on the collection tray of the BCM.

BCMs are designed with a number of features, including continuous agitation of the collected blood, automatic operation involving weighing the collected blood and stopping when the desired amount of blood has been collected. Blood collection bags also contain an anticoagulant and blood filters. Up to approximately 900ml of blood is collected in a normal collection procedure. Continuous mixing and agitation of the blood in the collection bag is essential during the collection process and this is one of the primary requirements that the BCM needs to achieve. The BCM should also continuously measure the weight of the collected blood. At the end of collection an automatic clamp is used to close and often also to seal the collection cannula.

Blood Collection Monitors are currently manufactured [5-9] in other countries and imported into Thailand. Patent protection on the fundamental BCM technology in most cases seems to have expired, and so there appears to be little restriction on development and manufacture of a "Thai" BCM to fill the needs of Thai hospitals. Questions to be answered include whether a "Thai" BCM is a good candidate for this type of development, will promote the Biomedical Device industry and is commercially viable.

Aims of the collaboration are as follows. Firstly, the project is concerned with how to transfer research knowledge to make a commercial product in Thailand at a price that is significantly cheaper than current commercially available monitors, imported from overseas. Secondly, the project is concerned with investigation of the potential for aspects of the collaboration to promote university students to be incorporated into undergraduate project work both at SWU in Thailand and UT AS in Australia. Finally, this is a good chance to initiate collaboration in biomedical engineering and medical devices between researchers and practitioners from both Thailand and Australia.

11. METHODOLOGY

We begin with how to design and implement a blood collection monitor corresponding to design requirements. Then we demonstrate implementation of two designs.

A. How to design a blood collection monitor (BCM) A standard blood collection monitor holds a blood

collection bag on a tray that is mounted to rock at a set frequency to agitate the blood in the blood collection bag for mixing the blood with anticoagulants. The weight of the blood bag is sensed to enable automated start, clamp and stop functions and there is a "user interface" comprising buttons (start/stop, bag size selection, pause), audible buzzer, an LCD display (collection time, error status) and LED (operational status). There is also mains power with a (rechargeable) battery backup.

A diagram showing the interconnections between the components of a blood collection monitor system is shown in Fig. 1.

LCD DISPLAY

i CONTROLLER

t CONTROL BUTTONS

- Mechanical ......- connection

r---------------,

ELECTRONIC CIRCUIT

LOAD CELL AMPLIFIER �

..I I

1 MOTORDRNER

--f+

TRAY

LOAD CELL

I ROCKING MECHANISM

I MOTOR

Fig. I. Block Diagram of the blood collection monitor system

From Fig. 1, the blood collection monitor can be split into mechanical and electrical parts. The mechanical parts comprise a tray, weight sensor (load cell), main housing (rocking mechanism, linkages, and automatic clamp), and electric motor. The electrical parts comprise, electric motor drive circuit, micro controller based control unit (micro controller and interface electronics), motor speed control, weight sensor circuit, power supply, buzzer, LCD display, control buttons, automatic clamp interface, and (rechargeable) battery backup.

Design requirements are as follows. A rock frequency is up to 0.42 Hz (�25 rpm) and needs to be smooth. The weight of blood is up to 900ml or 954g-specific gravity of blood (�1.056), and its flow rate through the cannula can be measured. The rock frequency and blood flow rate can be changed during the collection time. The desired amount of blood can be recognized, and the machine automatically stopped when a preset weight is reached by manual intervention.

To provide a smooth rock frequency, rotary motion provided by a DC motor is converted by a connection rod mechanism into a rocking movement. The mechanism also includes a load cell holder. The weight of collected blood is measured by the load cell. The choice of the load cell is highly

depended on the maximum load applied. For this application, the weight is relative small and requires high accuracy, so a bending beam load cell could be a good choice. For example, load cell GK2130 is a single point load cell with maximum load of 2S00g, and the accuracy is 0.02% capacity which is O.Sg selected. The rock frequency could be changed during the collection time by a controller. Since the rock frequency is provided by a DC motor, its speed will directly affect the rock frequency. The controller can provide a PWM signal via a MOSFET connected to the DC motor. The signal can be changed leading to the change of motor's speed. i.e. the rock frequency is changed. The current amount of blood is displayed directly via a LCD display. That amount is measured by weight in grams. The blood weight creates a force that affects the bending load cell. The load cell generates an electric signal which is read by the controller. The controller transforms this signal by an analog to digital converter and displays it on the LCD.

The tray holds a blood collection bag. Its side is made with an angle so that the blood bag would not fall over when it is fluctuating. It is designed with rectangular shape.

B. Implementation of the BeMs In this project, there are two BCM prototypes which have

been partially developed (Fig. 2). The BCM prototypes comprise a collection tray mounted through a connecting rod onto a load cell, and a rocking mounting for the load cell. The mounting is driven by an electric motor.

(a) Prototype I: a magnetic connection onto a load cell

(b) Prototype 2: no magnetic connection onto a load cell

Fig. 2. Prototyping the Blood Collection Monitors

A dynamic analysis of prototype I was conducted based on classical dynamics and the known motion and mass of the BCM (Fig. 3) and the collected blood (Fig. 4). Motion of blood within the collection bag during tray oscillation was assumed as shown in Fig. 4. This analysis was used to estimate the motor shaft torque required with up to 1 kg of blood collected.

Fig. 3. Blood collection monitor machines were created in the project.

Fig. 4. Assumed range of blood motion (B-B') for the dynamic analysis

Prototype 2 was tested using a standard set of weighted pendulum varying from 10 to SOOg (lOg increments). This weighted set (BAL066 set) [10] was used to simulate drawing blood from a donor through a cannula and into a blood collection bag, located on the collection tray of the BCMs.

Ill. RESUL IS

The BCM prototypes created for a tray with and without magnetic attachment are shown in Fig. S (a) and (b), respectively.

The calculated motor shaft torque of the machine prototype 1 is shown in Fig. 6 for three different motor speeds and corresponding tray oscillation frequencies. The dynamic effects mean that higher torque is needed at higher rotation speeds. The motion of the blood results in the waveforms being not pure sinusoids.

(a) Prototype I: a magnetic connection onto a load cell

(b) Prototype 2: no magnetic connection onto a load cell

Fig. 5. Blood collection monitor machines were created.

1.0 ,..----------------------

0.8

� 0.6

.E. 04 +-----__ch��A_------_,W_-4;\_ ::: 0.2 +------#'7-'..:::::"""'�\_-----__ur_-----"& ::I � 00 -k----�"'r-----�----___....F_---� 'iii -0.2 0

-: -0.4 H'r---F-J/-----------\-''''''==---y'--------­E -0.6 +--'\---"�--1------------'''-----.�-----­:;: -0.8 +-�---j'------------------

-1.0 -'---------------,---,------,-,-----,----------Motorshaft angl e (degrees)

-Torque at M at 25 rpm -Torque at M at20 rpm -Torque at M at 15 rpm

Fig. 6. Motor Torque at different BCM oscillation frequencies of prototype 1 Measured weights from the machine prototype 2 are

shown in Fig. 7 when compared to the standard weights of pendulum. Results show linear relationship except at the beginning of small weights.

600

soo � f. 400---------------� .. �----­

.;:: .:: 300 1:: � 200 +--------���-----------­� ;;: lOO�---__c��----------------

.1all!l:1rd weight of IlenduluflJ> (g)

Fig. 7. Standard weight versus measured weight of prototype 2

IV. DISCUSSION

The aims of the project have already been partially fulfilled. The design and implementation of the new Blood Collection Monitors have been initiated with 2 prototypes, and the collaboration has been started between researchers at S WU in Thailand and UTAS in Australia.

This BCM project is currently ongoing. While the prototyping of the BCM is relatively straightforward, it has had the benefit of increasing knowledge of the collaborators regarding of the detailed design issues. When the best features from the 2 prototypes are completely combined, the fmal prototype will be used in trails to assess its effectiveness as a blood collection monitor.

V. CONCLUSION

The BCM project is proving to be a very valuable process for exploring possibilities for industry-relevant international academic collaboration and developments. We are expenencmg that international collaborations are very rewarding, but maintaining good progress is a challenge when faced with pressing day-to-day commitments in our own countries.

ACKNOWLEDGMENT

The authors wish to gratefully acknowledge the contribution of Dr. Kampol Woradit and Miss. Supattra Dontree, Srinakharinwirot University, Thailand, for some knowledge of their design .

This research is funded from Office of the National Research Council of Thailand.

REFERENCES

[1] http://www.thailand.embassy.gov.auIfi1es/bkok/press%20re1ease %202011_ Colombo%20A1umni_ Eng.pdf

[2] C. Thaijiam, and T..T. Gale, "Optimization of Right Ventricular Conductance Catheter Configurations Using Finite Element

Modeling and Direct Search Algorithms," International Journal

of Applied Biomedical Engineering, 1(1),20-26,2008

[3] C. Thaijiam, and T.J. Gale, "The Effect of Myocardial Anisotropy on Volume Measurement Using Conductance Catheter Techniques in the Right Ventricle," ANZIAM Journal,

49, C733-C748, 2008

[4] T.1. Gale, C.R. Stack, P.A. Dargaville, "Engaging with the

Medical community in Biomedical Engineering research," Biomedical Engineering International Conference (BMEiCON),

2011, Page(s): 298 - 301

[5] http://www.asi-1ab.net/blood-collection-monitor.htm

[6] http://dir.indiamart.com/impcat/blood-collection-monitor.html

[7] http://www.remilabworld.com/Blood _Collection _ Monitor. asp

[8] http://www.genesisbps.com/blood-collection-monitor.html

[9] http://www.acmelabinstruments.comlBlood-Collection-Monitor.html

[10] http://www.142sure.com/product/40/baI066