Based on the MSP430 intracranial hemorrhage detection equipment (1)

1 Introduction

In China, there are many patients with traumatic brain injury in urgent need of where a substantial portion of intracranial hemorrhage in patients who failed to timely diagnosis, delayed rescue and therapeutic opportunity. thus appear after brain hematoma or cerebral herniation. enabling compression in brain tissue and the brain-stem is irreversible injury in real terms.

Near infrared intracranial hemorrhage detection equipment in a short time on intracranial hemorrhage to make an accurate judgement on whether to implement CT/MRI provides indications. You can significantly increase the chance of survival in patients with and nervous system function recovery. clinical mainly used epidural external haemorrhage (EDH), SUBDURAL haemorrhage (SDH), superficial intracerebral hemorrhage, its advantages are fast, accurate, non-injury, can be applied to aid, hospital clinical Department, intensive ICU and wilderness battlefield. But in China have not yet seen on the device-related reports, more mature equipment abroad mainly Germany Oicrain CRAINscan instrument production company, which is very expensive. We based hemoglobin on near-infrared absorption characteristics and long Bert a Bill law. design of a portable device. implementation of the human brain to directly measure the non-invasive, and timely monitoring of course changes and rescue treatment programmes.

2 basic principles

When you ignore the scattering media on the projection of the total absorption of the media in various mission uptake of linear superposition, according to the law, through the media Beer-Lambert intensity It incident light intensity I0 relation between meeting the following:

OD=-lnIt/I0=μcl

Where μ is the absorption coefficient, C is the concentration of media, l represents the optical path.

0D for optical density, when a certain incident light wavelength. OD is a linear function of media concentration. Normal human brain on both sides of light absorption is symmetric if there are internal bleeding caused by vascular rupture, local blood concentration increases the absorption of light: and increases week this side of the brain through the human body measurement of optical density to determine the existence of the patients with traumatic brain injury, cerebral hemorrhage as the need for further CT or MRI provides indications.

3 hardware design

MSP430 microcontroller for the device to control core, his output pulse signal driver specific wavelength LED produces near-infrared, near-infrared light source through brain tissue from detection probe of photoelectric sensor collection contains brain oxygen information optical signals, photoelectric conversion to electrical signals to the SCM, after the processed signal can be saved in EEPROM are available through the LCD display.

You can also set the signal through the USB port to your computer for further processing or storage. The system diagram as shown in Figure 1:

Figure 1 device system block diagram

3.1 detection probe

Probe consists of a light source, optical sensors and front-side conversion circuit, small round hole for fixed light source, photoelectric sensor is the same as in the Middle, LED light source selection, sensor selection S1226 series photoelectric sensor, the dark current sensitivity small, sensitive to high.

Light and the distance between the sensor set to average 40mm. probe depth is about detecting 3cm, lights and constant current driver, under the control of pulse signal time-luminescence detection of double-direction was realized. Interface design for the edge of the arc, and placing the light source and sensor parts raised, reduce leakage of light source, the remaining parts of the design is very thin, slanting edges, making it easy to bend, base material used for silicone and avoid fixed probe is to be tested, it does not apply.

Figure 2 test probes

3.2 host circuit

3.2.1 MSP430 microcontroller

System selection, TI company production of 16-bit MCU MSP430F149, highly efficient RISC architecture, there are 16 fast response to interrupt a maximum clock frequency of 8MHz, interrupt wake-up time is less than 6 microseconds.

Its monolithic integrated multi-channel A/D converters, analog comparators, timer, serial communication interface, NC oscillator (DCO), hardware multiplier, you can meet the application needs of the majority of devices. Its internal preset a JTAG module. has complete online debugging function, takes advantage of on-chip FLASH easily achieve software upgrade.

3.2.2 signal storage