Table 1.

Overview of studies on microclimate measurements at the user-seat interface and subjective evaluation.

Author (Year)	Participant Information	Research Methodology	Objective Measurement	Subjective Evaluation **	Conclusions
Liu et al. (2019) [26]	Single healthy university student Height = 1.74 m Weight = 58 kg	Approach to the foam cushion at two different speeds (slowly or rapidly).	Three HTU21D (TE Connectivity Ltd., Rheinstrasse, Schaffhausen, Switzerland) sensors placed at left mid-thigh, right mid-thigh and coccyx.	N/A	Transient increase in RH at the onset of sitting was an artefact due to moisture from a warmer environment interacting with a colder sensor.
Havelka et al. (2019) [27]	N = 16 (detailed information not available due to commercial sensitivity)	60-min relaxation 180-min on-road driving 60-min break 180-min on-road driving (changeover between drivers and co-drivers) Compare the following seats: Seat 1 (standard): top–woven fabric (twill), middle–reticulated foam, bottom–jersey knitted layer Seat 2 (standard+): top—woven fabric (twill), middle–nonwoven, bottom–3D spacer knitwear	15 SHT21 (Sensirion AG, Staefa, Switzerland) sensors in five sequences with three sensors per row	Five-level Likert-type scale for comfort evaluation. Use the redefined subjective evaluation scoring system (4, 6, 8, 10) to better distinguish between categories.	Seat 2 had better thermal and ventilating performance than Seat 1. Possible to resolve differences between similar seat formulations.
Olney et al. (2018) [10]	N = 6 (M = 6, F = 0), wheelchair users with spinal cord injury at C5 or below Age = 60 ± 10.7 years BMI = 24.75 ± 3.58 kg/m2	100-min sitting on four wheelchair seating systems: (1) solid strap cushion (2) perforated strap cushion (3) foam cushion (4) air cell cushion	One capsule-shaped temperature-humidity integrated sensor (FH2, MSR Electronics GmbH, Seuzach, Switzerland) placed under the right medial thigh Infrared thermal camera (T450sc, FLIR Systems Inc., Wilsonville, OR, USA) measures heating and cooling characteristics three times: Preseating (room temperature), after 100-min sitting and 5 min after the subject being transferred out of the seat	N/A	Strap-based wheelchair cushions had better thermal emission capability as both solid and perforate strap-based seating systems cooled down faster than foam/air cell cushions when vacated. Based on the single point measurement at the skin-seat interface, no significant difference existed in RH.
Yang et al. (2018) [11]	N = 26 Age = 20–26 years BMI = 18.33–28.09 kg/m2	Two-hour sitting on two commercially available pressure-relief wheelchair cushions: (1) air-filled rubber cushion (2) foam-fluid hybrid cushion	Four SH15 (Sensirion AG, Staefa, Switzerland) attached to the skin fastened by a single strip of surgical tape at the locations of ischial tuberosities and thighs	N/A	Temperature significantly differed between the measured locations, while RH showed no significant difference.
Liu et al. (2018) [28]	N = 8 (M = 4, F = 4) Age = 23.6 ± 1.3 years Height = 1.69 ± 0.08 m Body mass = 56.2 ± 10.3 kg	20-min sitting on the following chairs: Chair 1: fabric cover + foam, Chair 2: wood, Chair 3: leatherette cover + foam	64 digital temperature sensors (18B20, Maxim Integrated, San Jose, CA, USA) forming an 8 × 8 thermal measurement matrix	Questions related to thermal comfort, for example, “Did you feel any difference when sitting on the test chair compared to the chair used while you were waiting?”	Created a sensor-array-based body–seat interface temperature measurement system. Thermal performance of three chair compositions were measured and compared without disrupting participants. Temperature field at the contact surface was not uniformly distributed
Sales et al. (2017) [29]	Single healthy participant	15-min sitting on eight types of chairs: lyptus wood, plywood, polypropylene, synthetic leather, melamine laminate, polyester fabric, metal and medium-density fibre board	RTD temperature probe (on the seat surface) Infrared camera (ThermaCAMP640, FLIR Systems Inc., Wilsonville, OR, USA)	N/A	All seats exhibited a higher cooling rate within the first five minutes of being vacated by participants. There was a significant variation at the beginning of cooling stage, but at the end of 15 min, all the seats reached environmental temperature, except for lyptus wood and plywood.
Pron et al. (2017) [30]	Single healthy participant Age = 34 years Height = 173 cm Body mass = 75 kg	35-min sitting on the honeycomb-structured cushion	CEDIP (CEDIP Infrared Systems, Croissy, Beaubourg, France) Titanium infrared camera (The first infrared image was taken on the upper side of the cushion, the second one on the lower side, and the last one on the canvas of the wheelchair)	N/A	Cushion structure had impact on heat loss and dissipation
Liu et al. (2017) [13]	N = 11 (M = 6, F = 5) Age = 21–40 years BMI = 19.31–26.44 kg/m2	20-min sitting on either foam or gel cushion	Three HIH4000 (Honeywell Co., Morristown, NJ, USA) sensors under the left mid-thigh, the right mid-thigh and coccyx	N/A	Different cushion materials had a significant effect on RH profiles at the body–seat interface
Hsu et al. (2016) [31]	N = 78 (M = 39, F = 39) Participants equally divided into three groups (n = 26) Group 1 Age = 21.9 ± 1.8 years BMI = 21.6 ± 2.8 kg/m2 Group 2 Age = 22.5 ± 2.4 years BMI = 22.2 ± 3.8 kg/m2 Group 3 Age = 22.2 ± 3.8 years BMI = 21.7 ± 2.1 kg/m2	Two-hour sitting on the following three cushions: air-filled rubber, foam–fluid hybrid and medium density foam	Skin temperature and RH were measured with four digital sensors (SH15, Sensirion AG, Staefa, Switzerland) placed under the ischial tuberosities and thighs bilaterally	N/A	Foam-fluid hybrid cushions exhibited the slowest temperature rise in comparison with standard foam and air-filled rubber cushions. No significant difference in RH between different cushions and RH reached a plateau during the two-hour sitting period.
Kumar et al. (2015) [32]	N = 10 (M = 0, F = 10) Age = 36.0 ± 5.56 years Height = 162.36 ± 5.57 cm Body mass = 65.59 ± 9.25 kg	25-min sitting on foam cushion	16 NTC-type medical grade sensors (General Electric Sensors, Fairfield, Connecticut, USA) placed around the ischial and thigh regions. (four on each ischial area, two on each thigh and two on skin-seat pan interface on each side)	Participants were allowed to adjust the temperature by regulating the seat air conditioning system. User’s self-selected comfort was attained when there was no further request for any change between two adjustment periods (5 min each).	Thermal comfort was achieved when the seating interface temperature was lower than the body temperature
Vlaovic et al. (2012) [33]	N = 6 (M = 3, F = 3) Age = 35 ± 4.3 years BMI = 23.9 ± 2.4 kg/m2	90-min sitting on the following office chairs: Model 1: A notch for coccyx and prostate, 2-layer ploy urethane Model 2: 3-layer ploy urethane Model 3: mobile in 3D, 2-layer ploy urethane Model 4: Mobile in all directions, 1-layer ploy urethane Model 5: Standard, 1-layer ploy urethane	Six S-THB-M008 (Onset Computer Corporation, Bourne, MA, USA) probes (three on seat surface, two in seat and one to monitor room conditions)	N/A	Seat surface temperature was always higher than its interior temperature. Surface moisture on a seat was different from that inside the seat.
Liu et al. (2011) [34]	N = 11 (M = 6, F = 5) Age = 21–40 years BMI = 19.3–26.4 kg/m2	20-min sitting on three seats: (foam, gel mould and solid wood)	Three temperature sensors (LM35, National Semiconductor Corporation, CA, USA) placed under left mid-thigh, right mid-thigh and coccyx	N/A	The significant difference between the three measurement locations indicated more sensors would be needed to accurately represent the thermal characteristics at the body–seat interface
Cengiz et al. (2009) [35]	N = 10 (M = 7, F = 3) Age = 30–34 years Height = 155–189 cm Body mass = 51–87 kg	60-min on-road driving while sitting on seats with either ramie blended seat cover or polyester seat cover	Skin temperatures (PAR Medizintechnik GmbH & Co. KG Sachsendamm, Berlin, Germany) recorded at four places (thigh, waist, back and right bottom) Skin wittedness (PAR Medizintechnik GmbH & Co. KG Sachsendamm, Berlin, Germany) recorded on the torso back	A seven-point scale for thermal sensation and four scale for body moisture	Subjective evaluation and objective measurements were positively correlated in terms of thermal comfort. Waist and back areas had the highest temperature values. Ramie blended seat covers were preferable to polyester seat covers due to reduced skin moisture and improved thermal regulation.
McCarthy et al. (2009) [36]	N = 10 (M = 5, F = 5) Age = 19–41 years BMI = 18.67–27.33 kg/m2	60-min sitting on foam cushions	Five LM35 temperature sensors (National Semiconductor Corporation, CA, USA) and five HIH4000 sensors (Honeywell Co., Morristown, NJ, USA) placed under front and middle parts of each thigh and ischia tuberosity	N/A	Various measurement positions showed different temperature and RH responses.
Cengiz et al. (2007) [37]	N = 10 (M = 3, F = 7) Age = 31.8 ± 2.2 years BMI = 22.95 ± 4.1 kg/m2	60-min on-road driving while sitting on three different seat covers (velvet, jacquard and micro fibre), respectively	Eight locations for temperature (PAR Medizintechnik GmbH & Co. KG Sachsendamm, Berlin, Germany) measurement (under thigh, inner thigh, stomach, side of body, chest, waist, back and right bottom) Two locations (torso front and torso back) for the skin RH (PAR Medizintechnik GmbH & Co. KG Sachsendamm, Berlin, Germany)	Seven-point scale for thermal sensation, four-point scale for body moisture, three-point scale for comfort on seat back and seat cushion and four-point scale for sweat level.	Three seat cover materials showed no significant difference in subjective thermal evaluation and objective temperature measurement. Objective measurement had a positive relationship with subjective evaluation. Skin wettedness on the posterior torso was significantly different across the three cushions, while skin wettedness on the anterior torso did not. Skin wettedness played more important role in comfort evaluation than skin temperature.
Stockton and Rithalia * (2007) [15]	N = 5 (M = 1, F = 4) Wheelchair users Age = 63.8 ± 15.1 years	10–16 h sitting (mean = 14.00, SD = 2.83 h) a day for continuous seven days. Four types of cushion: Airlite, Kombat, Primagel and Systam	Temperature and RH probes (Gemini Data Loggers, West Sussex, UK) inserted into the core of the cushion	Four-point scale comfort rating	Subjective sensation of comfort was not linked with temperature and RH.
Bartels et al. (2003) [38]	N = 4 (M = 4, F = 0) Mean age = 25 years Mean height = 177 cm Mean weight = 70 kg	180-min sitting on either leather cover + foam cushion or fabric cover + spacer knit cushion	Temperature and RH sensors (detailed information is not available)	Four-point scale for heat, moisture and comfort sensations.	Textile cover and cushion type can improve sitting comfort
Ferrarin and Ludwig (2000) [39]	A health male Age = 32 years Height = 185 cm Weight = 70 kg	15-min sitting on four cushions: silicone gel pad, air-filled rubber cells, gel-filled bubble and foam-filled bubble	Infrared camera (TVS-2000, Nippon Avionics Co., Tokyo, Japan)	N/A	Nonflat surface cushions (air-filled cells and bubble-shaped surfaces) showed lower peak temperatures than a flat surface cushion. Gel-filled bubble cushions had lower maximum temperatures than foam-filled bubble cushions. Temperatures at the thighs were higher than at the ischial regions.

M = male, F = female. RTD = Resistance Temperature Detector. NTC = Negative Temperature Coefficient. RH = Relative Humidity. * This article also applied pressure sensor and pressure-related contents were put into Table 2. ** In the 5th column, the comfort/discomfort scaling standards were listed. If the corresponding trial was not evaluated subjectively, the content would be indicated N/A (Not Applicable). All cited papers are presented in reverse chronological order.More than two thirds of the retrieved studies (13/18) were published in the past ten years (2010–2019), while only five articles appeared (5/18) in journals between 2000 and 2009, indicating an increasing interest in objectively measuring microclimate changes at the body–seat interface. Among these, seven papers (7/18) compared the objective results with a subjective assessment of comfort or discomfort perception using scale-rated questionnaires [15,27,37,38], self-selected thermal comfort [35] or asking questions related to subjective sensations [28,35].