Functional wearability is the performance test of the device. PPG only tests the functions of optical components. Optical continuous light or pulsed light tests do not use real physiological signals. Before testing, you must confirm the purpose, definition, environment, applicable scope of equipment, processes, etc., are tested using the output signal of the erected detection system, and the test environment must follow the reference standard. PPG performance testing can be divided into as following:

(1) PPG receiving and emitting test: testing the stability and signal-to-noise ratio of LED and PD in wearable smart device PPG.

　　Stability is the detection of actual signals. The functional items of common wearable PPG can be divided into two tests: heart rate and blood oxygen. Heart rate detection is an item regulated by IEC 60601-2-47 and ISO 80601-2-61. There are static heart rate measurement, dynamic heart rate measurement, database heart rate measurement, and heart rate variability measurement, among which the database heart rate is measured by the International Standard Database (MIT-BIH Database), which is an arrhythmia database. It is also designed to detect PPG arrhythmia database. The detection is based on the literature Sološenko, Andrius, et al. This is a well-known medical engineering journal Model converts ECG signals with arrhythmia into PPG signals, and can divide all heart rate and blood oxygen tests into artificial and physiological signals, while blood oxygen tests are in accordance with ISO 80601-2-61. The artificial signal, physiological signal, special test are detailed described as follows:

(1) Artificial signals

     (1-1) PPG fixed heart rate accuracy: Heart rate accuracy under simulated PPG signals.

     (1-2) Accuracy of PPG heart rate variability: The accuracy of heart rate variability calculation under simulated PPG signals.

     (1-3) PPG fixed blood oxygen accuracy: the accuracy of blood oxygen calculation under simulated PPG signal.

(2) Physiological signals

     (2-1) PPG has reference annotation heartbeat database data: PPG signal heart rate calculation function in Database data.

     (2-2) PPG dynamic heart rate detection accuracy: The heart rate accuracy of physiological PPG signals under dynamic conditions.

     (2-3) Accuracy of PPG blood oxygen database: The accuracy of blood oxygen calculation under the database PPG signal.

     (2-4) PPG blood oxygen detection accuracy: The accuracy of blood oxygen of PPG signal under free movement.

(3) Special test

     (3-1) Under different vibration frequencies and skin, the test device generates signal measurement noise to verify that the test uses in the optimal situation.

Unlike traditional electronic motor products, wearable smart devices need to focus more on direct and long-term contact with the skin, which may pose a risk of allergies to consumers. In order to avoid problems affecting the brand image, product recalls, compliance with standards and consumer safety requirements. Safety tests need to be performed and biocompatibility items specified in ISO 10993 should be followed. The compatibility test is mainly to ensure that the wearable device products that directly or indirectly contact the human body will not release toxic substances during use, causing local or systemic cytotoxicity, carcinogenicity or reproductive toxicity, which will cause the human body to cause inflammation, immunity, toxic reactions, hemolysis, thrombotic reactions and other hazards.

PPG photobiological safety test: To detect whether the light power and irradiance corresponding to the light intensity of the PPG signal are harmful to the human body. Two types of tests are performed, such as the harm caused by ultraviolet light radiation to the eyes and skin and the skin heat hazard.

Physical and chemical properties of materials: Whether the physical and chemical properties of the wearable device material are harmful to the human body must be in accordance with ISO 10993-9, ISO 10993-13 (polymer), ISO 10993-14 (ceramics), and ISO 10993-15 (metals and alloys) To identify possible degradation products and quantify them. A toxicological assessment of all extractable substances and degradation products identified should be performed to predict the toxicological risks that the medical device being evaluated may pose during use.

Skin sensitization: Whether the skin-sensitive reaction of the wearable device under prolonged contact occurs for the following three explanations. 

1.Ingredient review through ingredient list and safety data sheet (SDS) to find potential skin irritants and allergens. 

2.Toxicologists perform exposure assessments and perform a series of checks, including in vitro assays and chemical analysis, based on the actual use of the product. 

3. Carry out skin irritation and allergy risk assessments based on test data and evidence-weighted methods of exposure assessment.