In order to assess the feasibility using our Snifferomyces cells as a diagnosis method, a device called "Snifferometer" was built to measure the status of fluorescence. The purpose of building such a device is to overcome the complexity, incalculability, and the high cost of using fluorescence microscope.

Construction of Snifferometer

Scheme of the Device

Figure 1 shows the concept of how the device works. The LEDs emit blue light on the liquid mixing Snifferomyces and sputum of the patient. Later, the photodiode collects the glowing light and transfers it into an amplified signal of voltage. Thus, by reading the number of voltmeter, the status of TB smelling cells in sputum can be detected.

Figure 1: Scheme of Snifferometer

Figure 2: Real prototype of Snifferometer

Circuit of Snifferometer

The photodiode converts the light intensity into small current, and op amp is needed to amplify the small current signal.

Figure 3: Circuit of Snifferometer

Wavelength

By looking up in the Table of Fluorochrome, the peak excitement and emission wavelengthes of EGFP are known, which are 488nm and 507nm respectively.

Blue LEDs are chosen with the dominant wavelength of 470nm.

And the responsibility spectrum of photodiode can be seen here.

Thus a high-pass filter is needed which has a cutoff frequency around 500nm. 483nm and 506nm

Test

Eppendorf tubes are used to contain the liquid.

Two filters were tested:

• LEE Filters 768 Egg yellow.
• LEE Filters 101 yellow.

Four sets

• Control: M9 medium with E-coli
• Test: M9 medium with E-coli overexpressing TagGFP2

M9 medium is used because it has low autofluorescence.

Figure 4: Measured data

• reduce background light intensity: right filter
• increase green light intensity
• increase the sensitivity of the circuit
• enlarge the area of fluorescent