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R&D Focus

HS3D, a Handheld Pesticide Residue Detector

Despite international standards established to limit pesticide residues, a test report from the U.S. Department of Agriculture in 2015 discovered that 85% of the crops were still detected with residual pesticides. To avoid consuming pesticide residues, consumers usually wash vegetables and fruits via various approaches before eating or cooking. However, there is no method to know whether these foods are washed thoroughly and the pesticide residues on them have been removed. To protect consumers’ health, ITRI developed the Handy Smart Vegetables & Fruits Pesticides Dynamic Degradation Detector (HS3D), the first device in the world to provide household dynamic detection for vegetables and fruits. It helps users wash clean the items and thus ensures food safety.

The HS3D is a convenient, portable tool capable of conducting dynamic detection of pesticide residues during vegetable and fruit washing. The design rationale is that since the washable pesticides dissolve into water during washing, HS3D detects the spectral absorption on the water in a sink or basin and thus estimates the pesticide residue concentration. This smart optical spectrum detection technique is of high sensitivity. Combining with the dynamic degradative algorithm, the pesticide concentration that varies with the washing time can be detected. Featuring Bluetooth and a wireless charger, the device can determine in a matter of seconds whether the amount of pesticides is within a safe range, with the lights on the wireless charger indicating the results. A red light signifies that pesticide levels seriously exceed standards and that the fruits or vegetables should be washed vigorously before consumption. A yellow light represents an excess amount of pesticides and further washing of the product is required. A green light, on the other hand, indicates either little or no pesticide residues and that the item is safe to consume.

ITRI researchers designed a chip that comprises a Fabry-Perot spectrum filter to identify the IR and UV spectral absorption wavelengths of the commonly-used pesticides. While conventional optical grating needs matching linear array light sensors such as CCD or CIS, the Fabry-Perot detector requires only one single light sensor, (e.g. a photodiode sensor) to conduct beam splitting. See Table 1 for the comparison. This technology increases the device durability towards vibration or collision and enhances the signal-to-noise ratio of light signals. Moreover, the design is capable of significantly reducing the existing module dimensions to within 5 mm x 5 mm x 2 mm. Such a size reduction allows the price to be more friendly and makes the device available for household use in instant detection.

Table 1. Comparison between the Fabry-Perot detector and optical grating technologies.

	Brand S	Brand M	ITRI’s HS3D
Spectrum Range	Vis-NIR (Raman)	UV-Vis-NIR	VIS-NIR
Size	25 mm x 75 mm x 125 mm	16 mm x 61 mm x 42 mm	5 mm x 5 mm x 2 mm
Spectrum Type	Concave grating (1200 g/mm)	Vertical grating using LIGA (36000 g/mm)	Fabry-Perot fabrication using MEMS technology
Optical Detector	Linear array CCD	Linear array CCD	Single photodiode
Note	A traditional spectrum solution Heavy and not easy to scale down into a portable device	Grating is produced by MEMS technology but it still needs to integrate with a linear array CCD to get the spectrum.	A chip-scale spectrum solution Easily integrated with an optical detector Highly resistant to falls or harsh environment

Current pesticide detections conducted in laboratories are time-consuming. ITRI’s HS3D, on the other hand, adopts Multi-Wavelength Spectrum technique and dynamic degradative algorithm for real-time monitoring of the pesticide washing process. The algorithm can furthermore avoid fixed interfering sources during washing, for instance, water from different zones, or the presence of fruit and vegetable cleanser (e.g. baking soda). Other than the general purpose of vegetable and fruit washing, the integration with a dedicated mobile phone App may enable daily data collection; thereby forming a household food diet testing system. It can also detect early stage of food spoilage, a service unavailable from current pesticide detection technologies on the market. With database expansion, this technology can offer new applications for guarding food safety for families.